I think what might actually result from all this, is that Russia will be broken up into smaller countries, stripped of its nuclear weapons, and
heavy sanctions will be imposed on them to pay for all the damage they have caused. Think Germany after WWI.
Who's going break them up? Whoever controls Russia's nuclear weapons can stop any effort like that by threatening to nuke the aggressor, so you'd have to have the leader of Russia (Putin or his successors) voluntarily give up their nukes, etc.
All the ~200 ethnicities that are part of Russia now.