China doesn't build coal plants because areas cannot afford nuclear. They do so because need they need stop gap solutions. Their new coal plants use supercritical CO2, and phase out older, less efficient and more polluting coal plants. Check out this thread by Chinese energy sector consultant David Fishman which states that the new Chinese plants are amongst the most efficient in the world: https://twitter.com/pretentiouswhat/status/16004256242919055...

He explains that these more efficient coal plants are not only motivated by climate targets, but also by market prices.

Even these new plants aren't going to be around forever. They're going to be phased out eventually as China moves towards their 2060 net zero goal.