What if the Fuhrer completed operation sea lion and eliminated the British capacity to wage war over the channel, this would have negated the Mediterranean, north Africa and Greece campaigns while given the Axis it's much needed secured communications on Malta.

The disposition of the British armed forces may have resulted in more troops being deployed to the eastern front Although, but would securing England be large drain on the wehrmachts manpower coupled with notorious British patriotism ?

On the other hand If Britain was knocked out of the war in 1941, an alliance between Russia and USA would be severely difficult to initiate without the desperate British to form the basis of the alliance. Thus resulting on all attention being directed to obliterate Russia and it's ability to resist giving the Germans their much sought after Living space eastwards.