>Many rust belt towns are going through this right now; my mom grew up in a rural factory town in southern NY that once had a population of nearly 10,000 — 50 y

>Many rust belt towns are going through this right now; my mom grew up in a rural factory town in southern NY that once had a population of nearly 10,000 — 50 years later, that population is closer to 500. And still dropping because most of the lots in town are unoccupied, rotting homes left behind when previous owners died that would be torn down if there was the money to do so, but there isn’t and it drags down property values of everything in the area. I do not think any city whether dense or not can survive 20X drop of population and remain livable. If anything surburban locations are easier to clean up - it takes only a few days to a couple of weeks to clean up single store house and lot. Imagine the mess if New York population dropped to 400k people? There is no way to maintain subway, road network and all other infrastructure with such small population. Skyscrapers and high risers require constant maintenance and will be danger to others if left unmaintained. Decaying rural home is danger only if you are in it or on purpose right next to it. Blast radius of falling high rise is quite a bit bigger.