States such as Colorado, with a 2010 plan and regulations that favor converting plants from coal to gas, are already well on their way to completing their plans. Whether the lifting of regulations on coal to bring down the cost will be significant enough to make much of a difference is the question, given the investments already made in the switch to gas and alternatives. Switching back is an expense in itself. Colorado is unique since it produces both coal and natural gas. within the state, which reduces transportation costs of both, unlike other areas of the country . 60& of Colorado's electricity is generated by coal and a quarter is natural gas. Front range mega cities such as Denver fueled by Public Service have already switched their plants to natural gas.
The human cost of loss of coal jobs is not minor, but it can be mitigated by retraining skills for employment in manufacturing, truck driving, and alternative energy. Coal jobs in Colorado are already down 36% in three years and the state has launched retraining programs for jobs in alternative energy, though such jobs pay much less than coal miners once earned. In Appalachia and the west, mechanized strip mining is replacing labor intensive deep mining. Job retraining may be the key to families at least earning a living wage, if not returning to the glory days of deep coal mining.
FYI: In 2016, the US electricity generation was 4079 TWh (billion kWh) net, 1380 TWh (34%) of it from gas, 1240 TWh (30%) from coal-fired plant, 805 TWh (19.7%)nuclear, 266 TWh from hydro, 226 TWh from wind, and 117 TWh from other renewables (EIA data).