One thing that seems missing is the notion of cities within cities. Los Angeles and Silicon Valley (which I'm familiar with) cannot be treated as monoliths. Instead you have districts in which one subculture dominates others.
In Orange County you may have areas that are dominated by unemployed housewives with lots of money. But you may have areas around a University that have a completely different flavor. Comparing Westwood (UCLA) to Boyle Heights (Ghetto) is a pretty stark contrast.
But I understand your meaning - similar to what Richard Florida and others are saying about self selecting societies.
At least people like me who live in the middle west can a) put themselves near an academic setting and b) can feed as much off of digital connectedness as possible to offset the effect.