not to derail your derailing, but "nation state" has a specific definition that I think is different than what you are referring to. China, India and the US are not nation states. Neither is Belgium. Japan is the largest.
> The state is a political and geopolitical entity; the nation is a cultural and/or ethnic entity. The term "nation state" implies that the two geographically coincide.
No, I'm referring to nation-states in specific. If you asked me for three major examples of why multinational empire-states are a Bad Idea, I would point to China, India, and the United States.
Though their are arguments to be made that China is a Han nation-state that simply forces everyone else to go along with what the ruling clique of Han want.
> The state is a political and geopolitical entity; the nation is a cultural and/or ethnic entity. The term "nation state" implies that the two geographically coincide.
http://en.wikipedia.org/wiki/Nation_state