Im not saying it will be a short game or that i would want to play a 20+ round game.
But if allies just go KGF its not likely germany will be able to actualy get russia as round 4 the allies will be knocking on the doors of europe.
In these scenarios the allies just have to make sure that they take out 1 axis player without the other becomming bigger then the combined might. Japan is pretty much capped at how much ipcs they can secure and the US can produce so much units its not realistic to capture them.
But yea it will be a verry verry long game.