Eurofed, I really like your take on this question.
Thankee.
Like Half There I had thoughts along these lines as well.
Great minds think alike.
The Allies no doubt will win.
Yes, the outcome is written as much as OTL WWII was after Pearl Harbor, the main issue is how much time and effort such a victory shall take. And in turn this is mainly dependent on how deep Russia manages to penetrate in continental Europe and the Middle East, and secondarily how welll the Allies manage to keep control of India.
The Pacific theater shall essentially fare as OTL, even if subduing China may easily be a long and difficult mainland counterinsurgence war even for an Euro-American alliance. Similar considerations if the Allies mostly lose control of India to radical nationalists. Hopefully for all parties involved, Chinese and Indian nationalists on one side, and the Allies on the other, realize that a compromise peace is necessary to avoid a bloodbath, and a sensible compromise is stricken between Chindian needs for nationalist self-determination and Allied needs for global security in Asia (and neo-imperialist needs to Asian markets) after Russia and Japan are done, otherwise there is even the possibility that the Allies lose patience with conventional counterinsurgence and use nukes to subdue China. On one side, the space for compromise exists if the Allies realize the need to appease Asian nationalism and Asian nationalists are quick to kick out the leaders most compromised with Stalin and the Japanese. On the other side, WWII was the time for ideological furor, so there is good potential that in mainland Asia, mutual rigidity like OTL Indochina sets in, and then the Allies shall subdue and "pacify" Asia with a bloodbath, either conventional or nuclear.
In the Atlantic theater, the main issue is whether the Europeans manage to keep the vital Franco-German-Italian core safe from the initial Soviet onslaught in the first 1-2 years of war, and contain Stalin in Poland, Scandinavia, and the Balkans. Same reasoning in the Middle East subtheater, although it is less vital for the Allies. Stalin has good chances to seize control of most of it (esp. if he stirs up Arab nationalism), and losing control of the oilfields and the Suez Canal would be very painful (but not fatal) to the Allies. Probably the Allies can keep control of North Africa unless the Euro core itself is overrun. However the Soviets have good chances to bully Turkey into vassaldom if they overrun Greece and/or Iran-Iraq. Keeping control of India may be a bit more problematic for the Allies if the Soviets coordinate with the Japanese or Indian insurgents.
If the Allies may keep control of the vital areas (Euro core, and to a lesser degree, India and North Africa), the story of the Atlantic theater becomes a long and titanic attrition war where the Euro-American superior industrial and manpower potential gradually out-produces, and then first stalemates then whittles down huge but inferior Soviet resources from Eastern Europe and the Middle East to European Russia. Hmm, as a guess, maybe 2-3 years for the Allied tanks to knock down the gates of the Kremlin, another year to complete the mop-up action of the Soviet space ?
If the Allies lose control of continental Europe, then it is questionable whether the US-UK alone can mass enough conventional resources to pull a successful Overlord. It is true that the Soviets would by then suffer a bad case of overstretch, having to defend the coasts of and provide occupation troops for all of Europe and the Middle East, and with usual Stalinist brutality, it is safe to assume that they would soon have a bad insurgency problem throughout Europe and the Middle East, even where they would have been welcomed as liberators, such as in the Middle East. They could make good use of the vast industrail potential of occupied Europe, however their manpower overstretch would not be lessened, in these conditions it is very doubtful that could draft any troops from occupied countries othere than some counterinsurgency militias drafted among local Communists. Small fry. In these conditions, the most likely outcome is that the Anglo-Americans manage to secure North Africa and maybe some peripheral areas of Europe, then raze European Russia to the ground with nukes when they get them.
But what will the postwar look like?
In the immediate post-war period, a gigantic effort by the Western powers to rehabilitate and reorganize ex-occupied countries and "democratize" conquered Russia, Japan, and their ex-vassals. Japan and Korea shall fare much like OTL, only with a longer Allied occupation. When the Allies discover evidence of Stalinist atrocities, Stalin and Communism shall become, if possible, even more reviled than Hitler and Nazism. The Soviet Empire is almost surely broken down much like OTL 1991 into a series of pro-Western client republics and Russia proper stays under military occupation for 5-10 years. A pro-Western regime is set into place, although a Putin-like right-wing authoritarian-nationalist resurgence is quite possible and even likely within the next generation (Russia is likely too big to accept the second-class power status that Germany and Japan did OTL). About the Middle East, India, China, and South East Asia, as I said above, mostly it depends whether the Allied governments and the moderate nationalists less compromised with Stalin can broker a decent compromise. If they do, such countries can acceed to independence with neo-Imperial Western economic penetration (see later for the possibility of a Cold War). If they don't, much the same result shall be reached after a decade of vicious insurgencies and counterinsurgencies down to mutual exhaustion that shall make OTL decolonization conflicts look like a firecracker.
One silver lining is that in this world, with a much stronger Europe, and no Communism, economic development of China, India, East Asia, Russia, and South East Asia, shall be significantly accelerated, even more so within Europe itself. One unfortunate fact is that ITTL, fascism, while gradually abandoned within Europe itself, may keep a strong attraction for Third World elites seeking for an ideology to motivate their nation building, and for a revanchist Russia. And later, so does Islamism within the Muslim world. And of course, more industrialization means more environmental troubles.
About Europe, Germany surely evolves back to democracy (quite likely a British-style constitutional monarchy) soon after the war, if it did not so before it. Italy, Spain, and Southern/Eastern Europe fascist-authoritarian countries shall follow suit later, the delay is dependent on whether Europe unifies or fragments into blocks, a federal democratic Europe would be an irresistible economic-political magnet and accelerate democratization of fascist-authoritarian countries, bloc division would prolong the lifespan of undemocratic regimes (say the range goes from half a decade to the dictator’s lifespan).
Culturally, Lenin/Stalin and Communism shall take the place of Hitler and Nazism as the face of absolute evil. It shall be a kinda more right-wing world in some ways. The same social forces that led America and Europe to create the Keynesian social democracy consensus shall be in place, even if one can expect Christian democracy to be kinda more influential about setting up the consensus than socialdemocracy proper. Likewise, the same social forces that created the youth culture, counterculture (even if it shall have a different surface ideology than the despised Marxist far left), feminism, and sexual liberalization shall be in place. However, ideas like racism (anti-Semitism going out of fashion rather quicker than prejudice against non-Europeans and prejudice against South and East Asians faster than the one for Muslims and Blacks), colonialism, and imperialism shall remain respectable for longer and go out of vogue only gradually due to decolonization fatigue. Europe shall remain as militarist (and possibly, non-secular) as the USA. Environmentalism shall still happen with rampant global industrialization, but it shall be much less of a far left-wing issue, or it may become the new core ideology of the far left. Multiculturalism, political correctness, hard-core pacifism, Western guilt complex shall never exist or remain fringe issues or dealt with Japanese-style denial. Eugenetics shall remain quite mainstream and respectable, and while this may spell abuses against disabled persons, it shall pave the way to accelerated biogenetic research. Human cloning, germ line genetic treatments for all common genetic diseases, budding “designer babies” genetic optimization of desirable qualities, and widespread industrial uses of manufactured microorganisms are not unreasonable to expect by the end of the century.
About the new geopolitical global order, the bread and butter of any true-blooded AHer (alongside wars, wars, wars), I see three main possibilities, depending on whether a) USA-Europe solidarity b) European integration can be maintained and developed or not.
Case 1, American and European elites can organize an efficient and mutually satisfactory partition of global markets. USA and Europe maintain wartime partnership, France, Benelux, and Germany do likewise and set up federal Europe as WWII common struggle buried old Franco-German antagonism, soon joined by Italy, Scandinavia, Hungary, Czechoslovakia, Poland, Romania, Spain, and Potugal. The UK clings to its fading Empire as much as it can, remains a good partner of both superpowers, but most likely does not commit to European integration directly, although it may claim a special associated status. A world eerily resembling a retro 1990s-2000s (with the decolonization conflicts taking the place of the Western-Islamist conflict) ensues for a generation, until the rise of China and India and a resurgent Russia force a multipolar shift. If any of the new powers embrace antagonistic ideologies like “fascism”, nativism, or aggressive nationalism, a new Cold War is sure to follow, possibly bipolar (e.g. US/Europe vs. China/Russia, with India as a swinger, or Russia/India, with China as a fence-sitter), maybe multipolar.
Case 2, American-European rivalry develops, over the division of global markets, even if the conflict may be masked in terms of an ideological colonial/anti-colonial struggle (with a lot of hypocrisy on the part of nominally anti-colonial America, as they shall prop their own neo-imperialist sphere of influence in East and South East Asia), but Franco-German solidarity and European integration occur as above. A bipolar US-Europe Cold War occurs as above, with the UK joining Europe most likely, the USA capitalizing on the strength of its South American and Asian clients for a generation, until the rise or resurgence of Russia, China, and India muddles the picture as above, as they pick sides, play each side against the other, or try to become rival centers of power. Note that if a USA/Europe Cold War develops, Canada and Australia shall be exposed to terrible geopolitical tensions, them abandoning the Commonwealth and joining the US camp is quite plausible.
I do regard both these cases as rather plausible, maybe 1 a bit more likely than 2.
Case 3, neither a or b occur, this is the scenario you described below, the US makes an alliance with some European powers against the others. This is possible but not that much likely IMO, the Western bloc is rather unlikely to fragment completely in light of all the global challenges that face it after *WWII.
Is there a Cold War-style bifurcation? Perhaps the U.S. and Germany will have a Cold War. Another intriguing possibility might see the U.S. and Germany establish friendly postwar relations and apply pressure on Britain, France, and Italy, who are pushed into an alignment over mutual defense of their colonies. In this scenario, the U.S.-German sphere will win, probably earlier than the end of OTL's Cold War. This WWII will make a particularly interesting 1960s in both the mainstream and the counterculture.