Assuming a near-infinite number of universes where this ASBish setup is replicated (Germany & Italy in control of the continent, yet at peace and not bothered at all by anyone else), what win percentage would you expect the Axis to achieve?
100%? (i.e. in every such similar TL, they defeat the USSR?)
66%? (about two thirds of the time)
etc etc
Personally, I would put it as follows:
- 15% if there is a serious risk of WAllied intervention, Stalin reacts to pre-invasion warnings properly, LL still takes place and the Germans get cocky from their previous successes
- 85% if none of the above is included
Allied intervention is a game changer, but it depends when it happens, because enough damage may have been done already to cause them to collapse. Soviet prep for invasion really isn't going to save them either in 1941. In 1942 sure, but not in early June 1941 (the Germans could attack sooner because of no Balkans/Greek campaign). LL is going to have a harder time getting in without the Allies being at war because Germany could declare a legal blockade of Murmansk and enforce it (probably even take it with the extra resources of TTL), while even compensation via Vladivostok doesn't work as well due to the distance it would need to travel. The Germans were already cocky from previous successes.
I don't think putting a specific number to it is really that valid but around 2/3rds of the time it would be an outright Axis victory with enough time (assuming just 1 on 1) and the remaining 1/3 or so would have an Axis favorable peace result. I cannot see the Soviets ever ending up close to their 1941 border, let alone over it, without allies intervening in the war. If Japan joins in the USSR is screwed. If the Wallies join in we'd need to know when and in what context, but I think that would be an exceedingly low chance.
Having more respources later in the war doesnt hurt Germany, but it doesnt help the critical phase, the second half of 1941.
The failure is logistical one - the road and rail net simply couldn't support a bigger army (it can be argued it couldn't even support the OTL one!).
You cant fix the rail net. You might get more trucks, and fuel (from where,exactly? The British and Americans arent keen on supplying it - and guess who pretty much control oil supply, and if they do will demand immediate payment in strling/dollars, which aren't available).
That is actually not true, the Germans did not put in the resources necessary to make the rail net work, partly due to lack of resources. With Britain out of the war they'd have the steel to complete the 'Otto Plan' to build up the rail net in Poland (the key bottleneck in the 1941 campaign), which fell by the wayside in 1940-1941 due to the need to spend on fighting Britain that was not planned on. Thereafter they have a lot more men and raw materials to put into logistics things that they lacked IOTL because they were investing heavily in Uboats, air defense (1/3 of the Wehrmacht budget went into AAA in the 2nd half of 1941, not counting civil air defense bunkers and FLAK towers), production expansion, Uboat pens in France, the Atlantic Wall, etc. Lack of manpower and resources was a constant problem for the logistics effort of converting rails and building it up; there is a limit to what could be done to fix the problem as quickly as possible and that was NOT done IOTL. Hitler also held back a lot of resources and replacement equipment/supplies because he was planning on a 2nd campaign after Russia against the British in the Middle East. David Stahel talks about that a fair bit in his book on the reasons for the failure of Barbarossa early on.
Getting more trucks is an issue of resource allocation and not being blockaded. The war would be over and unless the US declares and embargo of Europe (not happening) the US auto and oil companies could resume normal sales to Europe/Germany. Plus Germany could import from the occupied European colonial empires (Belgian Congo rubber and copper, Dutch East Indies oil, rubber, nickel, etc., whatever the French had) and neutral nations. The Iranian Shah was very pro-German and gave them a bunch of contracts to develop Iranian infrastructure from pre-war through 1941 when the British invaded and overthrew him; he warned the Germans in the country and they were able to flee via Turkey first. South America had a ton of oil as well (Venezeula, Mexico) which was available for purchase with looting gold from Europe; plus German companies now have access to their subsidaries in the Americas and the millions earned in foreign currency that the government could use to purchase abroad.
And the Germans did manage to counterfeit the Sterling:
https://en.wikipedia.org/wiki/Operation_Bernhard