Ghost cities are weird: first they talk about the ghost cities, then others say the ghost cities are filling up. If you actually visit, say, Ordos New Town, you'll really get that, no, those ghost cities really exist.
Some will fill up, like Pudong did, I get Tianjin's new financial district will also. But those in areas with little economic hope in the near term (Ordos and dying coal), they really aren't going to happen before the buildings become substantially rundown (given Chinese concrete overbuilding to make use of unskilled migrant labor, these buildings require a lot of maintenance and will look decrepit sooner rather than later).
I wonder how much percentage of all buildings are empty in China. In my visit I saw plentiful empty skyscrapers, especially next to decaying homes where people would still live.
Local governments have ways of telling, e.g. By electricity usage. You can also try counting the lights on at night to get an idea of apartment occupancy (a fun last time at the apartment complex I used to live in). Someone definitely knows, but you can be damned sure that this information is considered "state secrets."or
Some will fill up, like Pudong did, I get Tianjin's new financial district will also. But those in areas with little economic hope in the near term (Ordos and dying coal), they really aren't going to happen before the buildings become substantially rundown (given Chinese concrete overbuilding to make use of unskilled migrant labor, these buildings require a lot of maintenance and will look decrepit sooner rather than later).