A fair amount of evidence has emerged that the Russians were in fact massing for an attack on Europe and that German attack in June of 1941 was simply a proactive attempt to strike them before they were fully ready. As such, the Germans bought Europe four years before Russians over ran the Eastern half and saved the Western half entiredly.
Where things could have changed slightly, but significantly changed the war, at least in the East, would have been an earlier official policy (instead of the unuffocial policy that existed basically from day one) of arming Russian (and Ukrainian, etc) Nationalist groups and turning them against the Russians.
However, even without an official policy, about *half* the line company strength of even the SSLAH unit were actually "Hiwis" - Russians who switched sides - in the winter of 1941. Somewhere over a million Russians/former USSR citizens fought for the Axis against Communism.
If the Germans had one, there'd have been a Europen Union with Germany and France as the dominant economies. Oh wait... Huh.