The fact is, Trump is the least liked candidate, with the highest negatives in the field. He will lose the general election if he gets nominated. For one thing, in a one on one debate on policy, his shallowness on the issues will be glaringly obvious. Hillary or Sanders would cream him.
As bad a campaigner as hillary is Trump will make her look brilliant. Trump won't be able to control himself and will make ugly remarks about hillary's looks, or intelligence, and she will be off and running playing the "victim". The media will eat it up and the mushy middle will be manipulated into feeling sympathy for her. On top of that, once Trump starts attacking hillary about bill's lack of character and her failure to deal with it the Rats are going to start pointing out all his affairs with married women and the ugly things said in his divorce proceedings.