>The hypothetical invasion of England would have delayed German >operations for months, making even the limited success they >experienced in Russia doubtful, and might have precipitated an >early entry of the US into the war. A completely different >world.

Actually some historians believe the invasion of Russia was to show England resistance was futile.
It sounds laughable now, but after the disaster in the USSRs attempted invasion of Finland, Hitler had every reason to believe Russia would be a walk over.

Having to attempt an opposed water crossing (nothing is more difficult in war) over a terrible stretch of water, protected by a large, first rate navy, an RAF the Germans failed to defeat in the Battle of Britain and a people who were fighters. Hitler had every reason to believe invading England was impossible.
Course you can find historians to argue anything. And how come when they can point out why what happened was inevitable they can't predict the future?
Germany winning WW2 is by far the most popular alternate history subject. The books 'SSGB' 'Fatherland' and the film 'It Happened Here' come to mind; but there are plenty others.
The Sock