If no one else wants to burn coal, coal will be cheap. It's not that expensive to dig it out of the ground and transport, and most of China's coal is mined in China.

Any solution that doesn't involve everyone agreeing to care about the externalities of coal (air pollution and greenhouse gases) will result in someone continuing to burn a lot of coal.

That's assuming the main cost of burning coal is the cost of coal mining rights, which it isn't. Less demand doesn't make it any cheaper to mine it or transport it instead of leaving it in the ground (which are actually significant costs), and doesn't make it any cheaper to build or staff the power plant relative to alternatives.