I don’t think it was the fall of the Soviet Union that was the major event. I think it could be the rejection of collectivist totalitarianism on a global scale by most people.
That is perhaps another way of putting it. The result is, of course, the large nation states can’t hold it together any more. People are seeing that their governments aren’t worth the cost and can’t even protect them, which is the primary reason for government to exist, so they are looking for a way out.
I think you will see more and more secessionist movements as people become increasingly ticked off at their rulers. And I do mean rulers, because the people who run government certainly don’t act like the public servants they pretend to be.