I think there is a small chance if there is some disruptions etc… then we could get a real political crisis.
Really I think if Trump wins outright it may not be that big a deal, I think he just says whatever gets him in then he will act a lot more rational if he is elected (Jimmy Carter did this but no one remembers).
Say what you have to to get elected then do something else.
So far Zero presidents have kept their campaign promises.