The typical reaction seems to be: OMG, cities, where nobody is living!
But in reality, lots of real estate projects start with nobody in them, and then fill up over time. That’s not that weird. Sure, these are city-size projects, but China is a big country undergoing bigger shifts.
The bigger issue is the country’s apparent addiction to centrally-planned, investment led growth — a development strategy that’s creating inflation that’s becoming seemingly untamable. Despite the talk about “rebalancing” it’s really not happening. And at some point, the country will actually have created way too many homes (just like the US did, during its great government-subsidized, multi-decade boom), and it will have millions of workers who built those cities who don’t know how to do anything else, and so on. And that will create serious problems.
In the meantime, until it becomes clear that really nobody is ever coming to those cities — and it’s not obvious that that’s happening — this in itself isn’t a huge cause for alarm.