In regards to nuclear weapons, first of all in response to Willy's comments that a nuclear war need not be all that entirely annihilating, I would remind you that at least in Russia's case most of their nuclear missiles are multiple independent reentry vehicles (MIRVs) with total yields amounting to 20 or 30 megatons.

Secondly, I think we should establish countries that do and do not have nuclear weapons. The obvious ones:

The Soviet Empire of Greater Russia: ~3000
United Territories of America, Midwestern Commonwealth, SPQA: ~750 each
United Free Peoples of Free Asia: ~300 (probably more, since China is actively adding to their arsenal today and Free Asia is much larger and probably also added whatever weapons North Korea possessed)
French Republic: ~300
United Kingdom of Great Britain and Ireland: ~200
United South Asian Empire: ~200

Other countries likely to possess them at this point:

The Caliphate of Istanbul (let's ignore that Israel would have nuked them in order to remain in existence)
Greater European Confederation (unless they have a stance against them)

Countries that maybe could possess them, but unlikely:

Third Mexican Empire
Kingdom of Neo-Hungaria
Spain