The coal industry produces over 41,500 middle class jobs in PA alone. I guess you think that will be a miniscule loss to the middle (formerly working) class.
It might make a dent with the direct and indirect employment situation caused by this, but that it not the issue. The issue is the cost of energy should it skyrocket like Obama promised in 2008. The middle class can not take anymore hits to their expenses. That is what will cause the biggest loss to the middle class.