Just as the old churches, once so central that it was impossible to imagine life without them (if one even thought to try), so the centralized nation-state will eventually loose its relevance. What will it be replaced with?
One possibility is that various functions will slowly be duplicated by other actors, till these become the go-to address for solutions to real world problems.
So what remains to the state? At the end, all that is really core is, as per Weber, the monopoly on physical force. But even this, like the churches’ monopoly on spiritual belief, can lose relevance if physical force becomes somehow irrelevant, or impossible to apply, or counterbalanced by external forces.
If the circumstances discussed here do come about, it would not be far fetched for a U.S. Presidenrial election to about as interesting to the world at large as a convocation of cardinals: personally relevant to the believers, otherwise a yawn.