The only thing that will make Trump drop out, according to the Donald himself in an interview with Chuck Todd, is dropping in the polls.
Talk about intenstinal fortitude.
"Um, Mr. Trump, can I interupt your prep for your speech about everyone being a loser for a moment to fill you in on the latest poll numbers?"
"Just a second. What's better for describing Obama, 'gutless' or 'yellow'?"
"I'd go with gutless, sir. But just so you know, you're back to second place in the latest polls."
"I quit."