Its too vague of a term, doesn't have meaning.
You can break it out into the war on coal powered power plants like in clean coal versus dirty coal and the war on coal mining, and you have break out coal mining into thermal coal for power plants and metallurgical coal(metcoal) like making steel. Then you have to break it out for domestic used coal and export coal. And you can't really talk about coal without talking about natural gas
Before long you realize that to discuss the subject you will have to write a 500-1000 word essay on the subject.
It is much easier to go with the slogans like war on coal and drill baby drill
The term “war on coal” will catch on when electricity rates skyrocket and/or we have a blackout caused by lack of generating capacity due to coal powerplants closed by regulatory fiat. It’s coming.