The problem is that even if coal is completely deregulated, it's not miners who are going to be doing the extraction. The future of mining is automated. At best this will just give the coal barons a few more years of profit and do dick for the miners.
But it's not even going to be that good. Natural gas is killing coal, so there isn't even going to be a coal industry by the time renewables dominate. This is a classic "buggy whip" problem, in that there ain't gonna be no more horse-drawn carriages, so there ain't gonna be no more buggy whips. Whatever you think of Clinton, she was telling the miners the truth, their jobs are quickly becoming obsolete.
And the same goes for lots of other industries. Manufacturing is rapidly automating, so that even mass repatriation of US industrial capacity is not going to deliver the same level of employment that was there even thirty years ago. There's nothing the US government can do about it, short of outlawing automation and renewables, which would be sheer madness.
Christ, no less than Rick Perry himself has admitted the US needs to stay in the Paris Accord. Even the most pro-oil of pro-oil politicians know full well the jig is up. Oil isn't coming back, and as the price falls away it's impact on the economy diminishes. Coal was the first because it's the most expensive and most obviously harmful, but it applies to all the fossil fuels.