There's a chance that Romney will drop out and endorse Roemer, too, but not much of one. And there is not much of a chance that Perry will drop out at any time short of the South Carolina primary results. He has the money and the message to continue, so why not? And even then, why on earth drop out in favor of Gingrich of all people?
Your question was answered by untwist, here:
http://www.freerepublic.com/focus/f-news/2827594/posts?page=51#51