If Hitler had treated conquered Eastern European countries better (equal treatment, promising independence, etc), would it have been enough to bring down the Soviet Union?
- Less Soviet partizan activity -> more production and natural resources for Germans.
- More pressure/restlessness inside the surviving Soviet Union: Paranoid Stalin would have weaken his position even more by not trusting anyone (=killing everybody).
- Possibility to enlist more troops from conquered areas.
- Holding the major food production areas in the Ukraine - even couple of more years - may have caused a serious food shortage in the surviving Soviet Union.
- German image abroad would have been that of a "liberator" - more pressure to the western Allies not to support the Soviet Union.
And if that's not enough to turn the war on the eastern front, what else needed to change? (less support from the western allies, etc)