You're still not explaining which the Reich does not die of severe sunburn 1945-1946. And I'm not sure we would have to wait for nukes. Frankly, the Italian peninsula is a lot more defensible than northern France, and it's hardly like the Allies were putting their A-game into pushing to the Alps. Given the huge forces that would be required to garrison a defeated USSR (or keep an eye on some post-treaty rump USSR), it's doubtful they could have much more than doubled the overall forces in the west at the end of '44, and the US had reserves of manpower it hardly touched OTL (for all the meatless fridays and such, the US essentially pursued a gund-plus-butter approach to fighting WWII: it wasn't really squeezing industry till the pips squeaked, either). I suspect the US could still have forced a landing in France and pushed on to Berlin, although it would have been a real meatgrinder (and if there are any Russians still alive by that point, there's going to be a major revolt/attack by rump USSR at some point during the process).
Rousseau, the US use of nuclear weapons and threat of using more if the Germans don't surrender is going to convince the Germans they will be exterminated if they surrender and cause them to fight on to the point of Paraguayan losses? Color me skeptical. (BTW, with no second front, how likely is it the US will no longer insist on unconditional surrender? Truman just might be willing to go for a negotiated surrender before we move on to atom bomb large-scale production as long as it includes Hitler's head on a stick).
Bruce