In places like Lisbon and Milan, the rich live in the center and the young folks live on the outskirts. The outskirts then become trendy and cool and filled with bars and restaurants and cafes (can also look at Brooklyn, and now we are seeing a second Harlem Renaissance as well). Eventually the rich realize this and move to that place, and then the young people move again. But no matter what, the young people always end up living in the most desirable area because they commune with each other and create a desirable community in that place; meanwhile retired wealthy people are inherently uncool and consume more than they contribute.
The price of houses will fall and the price of basic services, food, etc. will skyrocket as people flee the stagnant cities and core economic activity moves elsewhere. It will never go this far of course (zero actual workers is an asymptote), but that's the way it will trend.
This is already happening in many neighborhoods in California. I imagine elsewhere in the US too. People who keep it running have to commute long distances.
