If we know anything about Clinton, it's that she will adopt popular opinion (opinions that she thinks will help her). I fully expect her to adopt some form of the rhetoric which has made Sanders so successful. Plus, she needs to, and will, spin Trump as a reason the middle class is losing jobs and money. I don't think his supporters are set in stone. Trump popular vote is about 13 million, Clinton is about 15 million, Sanders 12 million, rest of gop combined is 15 million or so. The Sanders supporters will come around once the threat of trump enters the picture. The gop is so fractured, I think it's fair to say their base is a lot more up in the air. I could see a lot of Kasich and Rubio voters come out against trump. I could see a lot of Ted Cruz voters stay home rather than vote trump. The only demographic trump likely leads is white male. And more than anything, white uneducated males. That isn't going to win the general. He'll win states in the South, but if Clinton proved anything, it's that she is pretty strong in the South. 126 million people voted in 2012. Reagan won by 9 or 10 points, I really could see this being much worse than that. The electoral votes are a different story though.