A thought, inspired by teh book Luftwaffe Victorious
The author basically posits an effective Luftwaffe with a strategic bombing arm, that's capable of, when combined with a more effective stalingrad, keeping the USSR from winning the war in the East (It doesn't lose either).
I have my doubts, but it does seem to me that the USSR might be vulnerable to attacks on its rail lines and refineries, although I am sure some one will persuade me otherwise.
Thoughts?