Likewise I can't see Mitt doing as well as everyone says, sure he'd be at 10% but it would be easy for Trump/Carson/Rubio to cast him like Jeb saying he's part of the past
47% of Republicans would still vote for him in the primaries, no matter whether he's a severely conservative Mormon who claims that Romneycare has 0% resemblance of Obamacare whatsoever or not. The reason why he wouldn't get to 50% though is not because he loves to trim his dogs in the storm on the top of his car or that he loved to bully gays in high school (and much less that his grandpa was a serial bigamist), but rather because of the car elevator in his house.
Now, I'd love to see Romney take down Trump in a debate. Besides Chris Christie, he's the only one that I could actually picture effectively doing so.
And yeah, I do put forward a 10,000 dollar bet that Romney would make Trump look really pretty bad.