The empty cities are interesting. People don’t want to live there because there are no jobs and no services. There are no jobs or services because there are no people. Sounds like an opportunity for the government to step in and create employment, e.g. move a big military contractor there to “bootstrap” the city.
Several countries in Asia are/were not only making new cities, but new Capital cities (Malaysia, Egypt, Indonesia, etc) and they have mixed results. Old city pull and inertia is so strong.