Normally, if Hillary says she "won't forget you," you start looking for a way into some kind of witness protection program. It's sort of like when a character in a mob movie promises to "take care of you." The endgame is implied. ...And so it is with America's coal industry and the people it employees.
Except, in the case of fossil fuels, Hillary isn't even going the double-entendre route. She's being explicit in her promise to destroy coal companies, and eliminate the jobs they provide.