Coal will dead in 20 years. The problem is that as solar and wind drop in prices, the marginal cost of operating a coal plant will be higher than the total cost of solar, so it won't make sense to operate a coal plant. Natural gas plants will be used when renewables aren't producing power. Why would produce electricity at 4 cents a KwH from a fossil fuel plant when you will be able to buy power at 2 cents a KwH from renewables.
industries die all the time. There are at least twice as many jobs in the solar industry compared to the coal industry. It's called capitalism and freedom. Don't whine when your economic industries get harmed by the free market, adapt.