Hitler smelled an upcoming struggle with Stalin, and I tend to think he was right.
He lost the campaign by a margin, - Leningrad-Moscow-Stalingrad,- bear in mind that the outcome at Stalingrad is more than a year after the outcome at Moscow,and Stalingrad is very far east.
With that line held, he would have sat on most of the USSR's production capacity, - probably in the region of 2/3rd to 3/4th. So IMHO, had he held that, the USSR would have been doomed.
The biggest issue about the U.K. IMHO is that they existed as an enemy. That bound down a stunning amount of troops and resources, - much more than ever used to get as far as the gates of Moscow. (70 divisions were used).
Then is the real factor of losses, but it's much smaller.....still:
- From July 1940 to Barbarossa, the LW looses more aircraft to just the RAF than to the USSR in the whole of 1944! And 1944 is a high production year there and the LW had as well lost air superiority over the eastern front.
- Losses in land-forces were not so great between 7/40 and Barbarossa, except in the mediterranian pocket where there were some. But not enough to make a difference IMHO.
-Axis losses (KIA, WIA, POW) in the med untill the time of Stalingrad & then Kursk were considerable. You are talking of 300.000 Axis POW's alone in Tunisia at the time of Stalingrad.
- Same goes to air and sea. Untill the turnaround in 1943, the Axis lost a lot on the western side,and 1943 marks the year when Uncle Sam (who in 1940 Hitler wanted to avoid war with at all costs) starts kickin in with a heavy boot.
