Say Stalin dies of appendicitis in 1920 (as in OTL he nearly did).
It seems likely with Stalin absent, that Grigory Zinoviev would have risen as the leading figure among the Bolsheviks (to those of you who constantly support Trotsky, he was very unpopular within the party and had practically no power base).
So...what do you think a Soviet Union under Zinoviev would have been like?