Nobody has mentioned this, but I think it could be a real possibility.
What if they decide to UNITE and decline because of his unprofessional nature? Could be a make-break moment. Sure, 24% of the repubs, and most of the repub base, are slurping Trump every chance they get. But he's SERIOUSLY bad for the GOP party brand. He pulled lindsey graham into a meltdown, where he called trump a jackass.
What if the party, and the 15 far-lagging-opponents, decide they don't care what the voters want and try to freeze him out?