Interesting book to read on the topic is Charles Murray's Coming Apart.

https://en.wikipedia.org/wiki/Coming_Apart_(book)

Very much like this article, Murray focuses only on US, however, this is a global trend. A person born in Koškovce, Slovakia will move to Košice for high school, to Bratislava to attend college, they'll find their first job in Prague, second one in London and after a short while they'll arrive at San Francisco.

It wouldn't take a big stretch of imagination to write a dystopian Sci-Fi about a future where members of Mensa live in extremely liberal city states in Bay Area while the dumb are gradually pushed out to failing hellholes with mad dictators in control.