Russia: I have troubles seeing the White Forces not winning in a CP victory scenario. The direct neighbors would have a great interest in stopping the red forces from winning. Considering how even Poland was able to beat back Soviet Russia in that timeframe OTL, I would cast serious doubts on any scenario that has the White forces losing with Germany, A-H and likely even British support. The end result would likely be a monarchy in a similar vein like the one in Germany or A-H, a powerful monarch with a parliament and democratic elements. There are two ways this can then continue. Either you go the revanche route or conciliation. In both situations Russia would likely need time to rebuild and without the massively important regions they would have lost through Brest-Litvosk, they would need time to even get back to pre-WW1 levels.
For a second round, Russia would need allies. The same participants as OTL WW1 would be the first on the list. At least Italy would likely jump at any military alliance with such goals and anything really that would bring it out of the persona non grata situation the Central Powers would put it in. For France, it is harder to see them itching for another round, with having paid one of the highest blood tools in the war, there would be little interest in going for it again. More likely, the British would try to continue their better relationship with Russia. If a second round is the goal, I could see Russia going in a similar direction as OTL Germany. Anti-Semitism was rampant there, and nationalistic fervor would be nothing new. Not nazis per se, or anything close to it. But a Right-Wing Dictatorship.
Conciliation would essentially lead to a recreating of the Three-Emperor-Alliance. Russia would likely be put towards focusing more on its Asian territories and put into conflict regarding China, Afghanistan or Korea.
Italy: They would get the full brunt of the hatred of the Central Powers. A complete persona-non-grata on a diplomatic level and treated in such a manner. Every petty insult or treatment that you could imagine could happen. Essentially, seen as the traitor of the victorious alliance and given no quarter or outreaching hand to come back into the fold. If they don't turn to fascism or something similar, I would be surprised. On a foreign level similar to Germany in OTL, first likely better relations with one of the other losers of the war, either Russia or France. Depending on which of them would actively try to reverse their treaties or is antagonistic to the CPs. The final result could be a Triple Alliance between FR-RU-IT or just a Steel Pact with either Russia or the Gallic brother France. Overall, Italy would have a horrible standing from prestige to reliability.
France: Having paid one of the highest blood tolls from the Great Powers, France would be reeling from another loss against the "archenemy" in such a short time. After the - let's call it what it was - purges following the Dreyfus crisis, I have a hard time seeing any kind of monarchist uprising happening in France. With the OPs declaring for his scenario, that the moderates will remain in power and no right or left putsch is going to happen, France will have a worse interwar period than OTL. From a political side, I would say the Socialists would follow a similar role as the SPD did for Weimar. One of the pillars of the state and overall work towards a reconciliation for eternal peace in Europe. After unification and under Bismarck there was a period of cooperation between FR and GER, Weimar had some similar events and I doubt that France would not have statesmen from a similar caliber as Stresemann. If Germany would reciprocate or make use of such attempts, is of course a different beast. Their worst relations would likely be with the British, who would get accusations of having abandoned France and not fought like them etc.
Their colonies would be a serious strain on their resources, and the OTL wars they had to fight to have them remain would likely take longer or be even more brutally fought. I tend towards the former as the more likely scenario. Maybe they will even sell some or give them in exchange for treaty alleviation or as guaranty for payments.
A-H: The victory would grant the new Emperor great prestige and with the reforms already started before the war started, I have problems seeing it going in any other direction. The biggest stopping block for easing up on the nationalities was the Hungarian part, but after the nationalistic block failed to deliver on their promises, the way forward was already looking better. I doubt they would make a 180 turn and go back to repression. Cross nationality parties were on the up and without the complete crumbling of authority and military breakdown, there is no sign of the ethnicities starting some war to split the Habsburg Empire up. Every part of the empire wanted reform, not destruction or revolution. And it is highly likely that would happen. A perfect compromise from the get-go, not likely, but progress? Most definitely. Frankly, it is ludicrous to suggest it would crumble. Every successor state in that region was worse off and even ardent Czech separatists would look back in the interwar years and acknowledge that it was better before. The story of A-H being the next sick man of Europe is utter nonsense, and anyone postulating it has no idea what he or she or them is talking about.
As the second most powerful victor, they would demand a say in the future of Europe. In OTL there were already long discussions about every scenario for Poland and other territories. Germany would not get its way all the time and would have to make concessions. Essentially giving A-H a part of the pie. With Italy beaten, they get their say in Albania and the Adria will be their turf. The relations between these two states will be hostile and I don't think there will be even an attempt made to change that. To emancipate and lower German influence, A-H would likely try to improve their relations to old allies like Britain or the new Russia. Also, on the Balkan they would likely be a consistent and strong ally of Bulgaria. As the only state without any territorial aspirations on their land, it is a natural partnership, that would mostly be harmed by the common Austrian-Hungarian arrogance in regard to minor players. But maybe learned something...doubt it but hope never dies.
Germany: The big winner and undisputed hegemon on the continent. Their economic power would allow them to create an informal empire in the newly created states and further expand into the OTE. In combination with their plans for a bigger economic block, it could easily cement an economic block stronger than anything else at the time. If the Mitteleuropa plan would come into reality, depends on the circumstances. You would need concessions to the other nations that you want to join up with the exception of the newly created Eastern ones. They would not get a say, initially.
It could easily be that the CP would be turned into an actual military alliance with the eternal Dual-Alliance at its core. Bulgaria should be a near certainty to be added to the Dual-Alliance, similarly to the way Romania was once added or asa revival of the Triple Alliance with Bulgaria taking Italy's place. The OTE would share its place as a target of investments with the newly created eastern countries. Britain and Germany would likely compete towards economic projects there, but Germany should get some primary thanks to being a former ally.
On an internal level, the victory would increase the prestige of the army and ensure their utter primacy compared to the navy. They literally proved near completely worthless in the eyes of the people. With the U-boot being the major exception, they would likely be the future mainstay of the navy. For Prussia, the reform of the elective system was already in the making and discussed for a long-time. It was coming, just the details were in discussions. With such a boost to prestige and the proponents of a "Siegfrieden" vindicated, the chances for the conservative proposal to pass higher than for the other option. They had the House of Lords and the parliamentary majority on their side, add-on nationalistic feelings in regard to a victory, and they would likely carry through.
Finally, Germany could turn towards military dictatorship in line with the many other that existed in the OTL interwar-era or a slow process of reform continues. With the parliament slowly gaining more rights till they hit a maximum and an unsteady balance would exist. Or things continue as was before.
OTE: The victory should allow them to continue the path towards a stable future instead of crumbling into nothing. As a prime target for investment and with direct control of many regions that hold the black gold, there are paths open for a better future. If it goes that way, is not a given. But the chances are better than before.
Bulgaria: The new big kid on the block. Bulgaria would gain what they desired and maybe more. New territory, reparations and weaker frightenend neighbours would allow them to exert an amount of influence they had never had before. As part of the victors and likely a future partner of them, they would receive economic support as much as A-H or Germany can stomache. While being the least developed of the three European powers, they would profit from the downturn of their neighbours. Depending on when the war would end, all Balkan nations could be in a worse position compared to them. Serbia is finished either way, but Greece and Romania could also end up on the chopping block depending on if the the POD would allow asure the change or not. Regardless, both would face a Bulgaria strenghtened compared to the Balkan wars. Conflict would likely be in the future ahead, either as a revanche or because Bulgaria wants more. With CP support, I think they would get what they desire and at least A-H would be standing behind them.
Greece: Depends on war entry or staying neutral. If they entered war, they lose the lands Bulgaria wanted. The king would go out of this scenario smelling like roses, he was proven utterly fucking right and Venizelos wrong. If they stayed neutral, they would keep their lands but Venizelos was still proven wrong. His party would lose the next election and Greece would try to regain German favor. With the familial connection some German support should allow them to stop Bulgarian ambitions from turning things ugly for some time. Still the Balkan would remain a powderkeg and I think Metaxa would still come to power.
Serbia: Horrific, is a nice term for their fate. For all the blood lost they have nothing to show. A-H would not try to annex it, the supporters of this idea were always a minority and after that war they would not want to bear the cost of restoring it. Famine, death, anarchy. The country would be devastated and no support or anything would be provided to help them out nor other regions to exploit. It will be a non-factor for a decade, if not more. Constant troubles and bad things happening inside its borders.
Britain: Business as usual. The Irish War of Independence would still happen. Their Empire would still exist and the diplomatic game would start anew. I think relations with France would be the worst by far. Considering they would not be a loser just not the ultimate victor of the war, they could shoulder the aftermath. I don't see big upheavals coming their way. Maybe try to establish their own alliance or sow discord in the victorious one by competing with Germany in OTE, Bulgaria and Russia. Or align closer with A-H in the Mediteranean against Italy or just to strenghten the position of A-H compared to Germany.
Another possibility is a closer alignment to the US or with Japan. Either way their more independent parts of the Empire will likely want to have a word with them regarding some changes.
