This is more of an irreversible economic trend driven by two factors...
1) The low cost of natural gas due to fracking and the addition of many natural gas powered electric plants.
2) The policies of the Obama administration forcing electric companies to take coal fired plants offline or add expensive C02 filters are at this point irreversible. The capital investment cycle for utilities is lengthy and most are walking down the natural gas path.
That's what the Dems were telling trumpers when he promised reopening of plants and easing of regulation. So why aren't the jobs coming back and the Mills turning?
Not going to happen the electrical power sector. Hard coal is coming back in the steel sector. We are seeing increased use of coal outside the electrical generation sector. This however only brings a few jobs back. Better than what Obama was doing which would have ensured all of their jobs would be gone.