Donald Trump is not going to get elected. Herman Cain was never going to get elected. Ron Paul was never going to get elected. Much like Bernie Sanders is never going to get elected, Ralph Nader was never going to get elected, ... The extremes get attention, and are exciting/terrifying if you lean far one way or the other and haven't burned out yet, but they never really have a chance.
I would be shocked if Trump won the primary, but if it came down to Trump and Clinton then yes. Committed Republicans will vote for a clown if he has an (R) next to his name, but committed Republicans alone aren't enough to win a presidential election.
I am not very motivated to "support" Hillary Clinton, but if Trump were her opposition candidate I would be much more likely to be a "supporter" of her