That's my thought as well, although I think Gingrich/Santorum might try for a ticket with just them if they've got 50% between the two of them.
Unless Paul were to throw his support at Romney, I don't see Romney winning a contested convention. There's simply too much "Anyone but Romney" sentiment out there for ROmney to get it any other way.
Frankly, I think a lot of conservatives are misreading "the GOP Establishment". For the most part, they don't like Mitt because he's Mitt. They like him because they just want to win, and they think he was the most electable guy. But I think the depth of the "Anyone but Romney" sentiment probably has caused some of them to reconsider that, and look for someone more acceptable to the party as a whole.
Ron Paul is staying in this race for one reason only -- to have a seat at the table come convention time.
He'll have delegates...and he'll sell them to the candidate that offers him the most. Romney, most likely.
It's a real good reason to minimize the Paul vote (except in Virginia).