Will Coal Make a Comeback in the U.S.?? in China??

The short answer: not likely. 

According to forecasts last year by the eia (U.S. Energy Information Administration), coal production will at best be flat vs recent year production levels; more likely levels will continue the downward trend of the past decade due to replacement by natural gas and renewables for energy. Employee levels associated with coal have also been declining and would thus continue to fall in future years. In fact, the headline of their forecast says it best: "Future coal production depends on resources and technology, not just policy choices." 

To summarize as they say.....'the train has left the station...and it's not loaded with coal'.

But the U.S. is not the only country that will be moving away from coal for energy.  China's government is now taking an active role in cleaning up their air. That's a good thing for everyone. China is the world’s No. 1 polluter: it burns more coal than the rest of the world combined. It produces more than a quarter of the world’s human-caused global warming gases.

China's plan is to provide a giant market where companies could trade credits for the right to emit carbon emissions. If it works as intended, it would give power companies a financial incentive to move to cleaner emissions.

Will it work? That is yet to be seen. But the intent is clear--i.e. coal is not the fuel source of choice in the world's largest market for the future. 

The train.....is leaving without coal in China too.

https://www.nytimes.com/2017/12/19/climate/china-carbon-market-climate-change-emissions.html