Eh, let’s give Christie, Kasich, and Bush until New Hampshire at least, since each of them has polled decently there recently at one time or another. Huckabee quit, Fiorina and Santorum are done, though.
After New Hampshire, at most one of Bush, Chrstie, Kasich, and Paul should remain.
I assume Carson is going to try to hang on until South Carolina at least, although with no NH/SC events scheduled, I’m not sure why. He’s essentially just playing spoiler at this point.
The scuttlebutt that I've read says that Carson's campaign manager isn't the good kind of guy, and is simply using the campaign as a way for them both to make some easy money. If you're already telling everyone that you're leaving the campaign trail "to go home and get some clothes"... http://www.nbcnews.com/politics/2016-election/ben-carson-heads-home-fresh-clothes-after-iowa-n509301.... it's time to bow out gracefully. Hopefully someone has a spot for him in dismantling ObamaCare.