Or, on the other hand...
In my previous post, I suggested that all countries under 10 million people (which include some troublesome ones) be disbanded.
I'd like to offer an alternate idea, which is that counties be CAPPED at 10 million, and free to form alliances with other 10 million-person countries without regard to geography. So the US would be about 30 countries, China would be about 120, etc. The UN would have about 650 members.
You'd probably have a fair number of Libya-style dictatorships, but my guess is you'd also have a bunch of NYC-style plutocrat-friendly social democracies. And you'd probably quickly have an international alliance of major metros (Bejing, Rio, Moscow, NYC, London, etc) that would soon run the entire world.
Hmmmm....