You know, I think what has to happen here is the Soviet Union goes democratic in WW2.
That's not as bizarre as it sounds. If Stalin dies, the whole Soviet State could well have a meltdown. Do not forget that Alexandr Kerensky offered to help the Soviet Union during its invasion--suppose that Stalin dies in 1943 and the disorganization leads to terrible routs of the Red Army?
And then, with Germany seemingly advancing towards Moscow, The Soviet Government renounces all of its ideological prerogatives with the single goal of surviving as a nation.
The Soviet Union, by 1946, has emerged as a shaky leftist-socialist government that ultimately goes Democratic, and remains allied with the West.
Such a situation would lead to early democratization of Eastern Europe; it could well turn into a global impetus for democracy globally.
That means no cold war, no iron curtain, and with some kind of RoC forming and Mao withdrawing to Xinjiang, and Democracy simply having a extremely strong hand. Completely plausible, if somewhat utopian.