airpig,
If Hitler wasn't Hitler you may have been right. If he'd consolidated his position in western Europe for a few years things might have been different (although they were still relying on horsedrawn transport in 1944).
He was a compulsive gambler, always looking for more as soon as possible. Barbarossa was always his 'end game' requirement for WW2 (see Mein Kampf)
p.s All that is on the proviso that the Soviets sat on their thumbs expecting nothing to happen in the interim. Even still Germany in 1940 had a population around 60 million, the USSR around 170 million. Do the math.