>The whole region could turn into something like Mexico City (wealthy center protected by police, surrounded by miles of slums and shantytowns). Importantly, people who serve key roles - teachers, service workers, etc.

Mexico City? That's almost every major US city already. Have you been to DC recently? That's it to a T. The government sector is nice, with a little buffer of upper class homes and businesses surrounded by miles of high-crime slums.