It seems pretty plain to me what a Trump candidacy looks like.
Months and months and months of fear setting in. A historic number of young, moderate, minority, liberal and female voters turning out with the specific goal to keep him out. #StopTrump or some variant is an inevitable movement - one that is probably going ot be bigger and louder than Occupy Wall Street , Obama's Hope campaign or Black Lives Matter.
Donald Trump probably has the hardcore support of like a third of the Republican base and the enmity of a quarter. Every liberal and moderate in the damn Country are going to turn out to make sure he loses, and some of the Republicans are going to swing.
It's going to be a historic loss. Much, much worse than any of the other Republican candidates - who would inspire more apathy among leftist voters, and less antipithy with the Republican party as a whole.
The lunatics voting Trump are loud, but they're not legion. Legion will be what opposes him in the general.