uuhhh dezrtfish, germany invading poland is what started the war. any ways back to the topic. You have to look at the industrial side too. Germany needed russias wheat, steal, oil and whatever crap is in there. If germany didnt invade russia they would have died out alot sooner from the hands of the us and uk. I know germany didnt beat russia but they got far enough to secure vital steel and wheat and some oil. Germany would not make it againts the US and Uk in full war time production. Germany barely had a war time production until 1943.
And for tanks like the tiger 1 and 2 forget about them. the germans only made these to counter russian tanks so its safe to say if they didnt fight russia the tigers would be a thought if some dudes head.
lets say germany takes africa and britan, germany is sitting very pretty right now because the US,even with their A-Bomb, did not have a stating post for invasions and no american plane could fly with an atomic bomb all the way to berlin, its impossible!