Major cities may have densified from the beginning of humanity until downzoning; it doesn't follow that they will continue to do so. We're not talking about living in the woods here; there are plenty of third-string "cities" with cheap real estate.
>Are you gonna make play remote too?
Especially among SF tech workers, play mostly consists of leaving the city for nature sites and hiking/camping/climbing them.
>Dating?
Small cities and towns reproduce at a much higher rate than elite coastal cities. Some of those matches may have been made in college or while working in big cities in early adulthood, but the educated reproduce less. So, apparently yes.
>Art?
Hollywood, television, audio reproduction equipment, the Broadway tour, the music tour, and traveling exhibitions between art museums made art remote. Small, cheap cities often have thriving (though less nationally famous) local theater, ballet, symphony, and opera, as well as visual/performing arts venues capable of receiving more prestigious national tours.
Smaller communities may even have strong community/educational theater traditions and spaces, which while not exactly High Art, are a lot more personal and participatory than anything you'll pay $200 to see in Manhattan. Theater in small cities/suburbs is unique among the art forms in that average people get to work on reasonably high production value projects and present them to their peers and families. Tight real estate markets can't allocate so much space to amateur performance, and it's easier to put an awesome lighting rig in a high school auditorium when you don't have a homeless population.
>Dining
I guess the dining culture is more about what you cook, who you cook it with, hosting potlucks and BBQs and dinner parties in your enormous house and backyard, etc.
>Music?
Any tour that passes through the likes of San Francisco will pass through the likes of Milwaukee, and if not it'll certainly go to Chicago, an always-fun and usually-accessible jaunt from smaller Midwestern population centers.