If Carson's campaign falls apart completely, it's a pretty big story. He still has about 10% support, both nationally and in Iowa. Presumably the remaining Carson diehards are evangelicals skeptical of Cruz or some such combination.
Cain dropped out still above 10 percent. Everyone knows which direction this ship is going. I doubt Carson will get anyone to come on as a replacement.
He should drop out now. He'll wield more power as a courted endorser in Iowa than just stumbling to a 4th place finish.
