@Schroedes13 I am not sure what you mean exactly about transferring more or lest troops from the west. That is not one of the major issues I think of as a tipping point for the Eastern Front.
History happened the way it happened, and hypothetical discussions of critical moments, chances of different outcomes, and what those outcomes might be, can only have a limited amount of accuracy to them. They are interesting, but I think one needs to keep in mind that there were many factors that could swing results to be very different, and one change would mean everything else could happen differently, too.
Hindsight is also a huge factor, as it were. Looking back, we can make observations that “if X had happened instead, Y would have been very different”, but we can see things like that which the historical decision makers could not or did not see, even though they did see many details which were also crucial, sometimes brilliant, and some of which may take a lot of research to appreciate, or even be lost to history.
For example, I would say that if the Germans had brought a large supply of winter clothing, antifreeze, and other preparations for a severe Mud Season and winter in Russia in 1941, and everything else went as well for them as it did, then they may well have knocked Russia out of the war in 1942 or 1943.
For another type of example, if they had not been evil to the Soviet populations in the regions they occupied, and if they had welcomed help rather than acting like, well, evil murdering genocidal facist Nazi bastard racist overlords, they could have had many willing allies and volunteers, instead of partisans sabotaging their rear areas.
Or even in the Winter of 1942, if von Manstein had been in charge of the southeast front and had been allowed to withdraw Army Group South from Stalingrad and conduct tactical withdrawals and counterattacks as he saw fit, and then in 1943 if the Germans hadn’t been baited into a meat-grinder at Kursk, 1943 could theoretically have gone well for the Germans.
Another example: In the US war with Japan, the naval battles of Coral Sea and especially Midway could have gone against the US if scout planes had been in different places at different times, tipping the balance of naval superiority against the US.
What would have happened to the world, though? I don’t see it as likely at all that the mainland USA would be captured or even invaded before 1945, when the US were able and willing to deploy atomic bombs. If Germany had defeated the Soviets in 1942 or 1943, they might have had it too. What would have happened then? A nuclear and/or cold war between Nazi Europe and the US?