Metropolitan areas grew up in specific areas for a reason. Shipping and receiving goods. Industry built along waterway, natural ports, rail hubs and highways. The ports which are automated in most countries no longer need masses of workers. The industries that needed workers in those regions no longer exist or are much smaller. When Blacks from the South flooded the North they were seen as cheap labor, they have since been replaced. We moved to a service industry economy and the cities have become $hit holes. The middle class and above moved to the burbs. Now the burbs are being taken over with low income housing and crap schools. What middle class is left are following the upper class out of the States. Consequently to retain control RAT governments, State, Local and municipal, started giving $hit away creating an entire class of leeches. Very slowly but noticeably the feral entitled class are taking over cities turning them into dung heaps. Eventually you will be left with metropolitan dystopian societies.
You lay out most of this death spiral rather accurately. Part of the cycle has also been buying parts of the dilapidated city at rock bottom prices and rebuilding it. They call it gentrification like it’s a bad thing.
The working, and entrepreneurial classes will move back in and drive the riffraff outward.
EC