Well, I'm thinking that without the rest of the Western world having that inter-war period to make Germany look Third World, it could have had enough of a force to challenge Russia (hell, had Hitler not interfered with the generals and Russia not had a sudden infusion of Siberian Commandos, Hitler might have taken Stalingrad and/or Leningrad...). With the Eastern Front more or less settled (a mid-revolution Russia would be shaky to rule, but much easier to keep under your thumb than fucking Stalin-era Soviet Russia) at the Urals, Germany could devote its full force at the Western Front. With American riding in mid-war like they always do, thinking they're Big Damn Heroes, the Front settles mere miles away from Paris.
This stays more or less static (with constant entrenched combat, but little ground gained or lost) as the Empires of France, Germany, and Britain fight proxy wars through their territories, colonies, and satellite states, a sort of Cold War within a World War.
Meanwhile, two downtrodden soldiers, one German named Adolf and his erstwhile guerrilla friend, a Russian named Josef, come up with a daring plan to end the war...