It wasn't the mistake of invading Russia, it was the mistake of fighting on 3 fronts. If he could've sprted out a Chamberlain style peace in our time again with the British then he'd have freed up many more resources from Western Europe and Africa to focus on taking on the Russians. They came...
There's a Black Book called the Sonderfahndungsliste G.B which was issued to special SS units. This contained a list of all those that were to be arrested on a succesful invasion of Britain. You still buy a reprint and it makes quite scary reading.