NG would require a substantial capital investment; running pipelines everywhere is not cheap. It might still be cost effective if the environmental costs of coal burning could be internalized so that coal-burners paid a price, but China seems very far from a Clean Air Act, let alone a cap and trade regime.
No one yet knows if the geology is suitable for extracting the gas. Testing is just beginning. Just because there is gas does not mean it is economic right now. Fracking technology is very new.
They have 886 trillion cubic feet and the USA only has 750 trillion of it.
http://www.foreignaffairs.com/articles/138597/aviezer-tucker...