I argued months ago there is a plausible scenario where even if Bush hasn't won any states, he stays in and bets on Florida turning it around.
You do realize that 25 states have primaries or caucuses before Florida does? How is winning his home state going to turn things around after he's just lost 25 contests?
If Trump (or Trump and Carson) is sweeping the primaries before that, the establishment will still try to stop him (or beat both) and there will be a sense they're fragile until they win.
Bush could be the establishment horse at that point if he's outperforming every other option and outpolling them in Florida.
Bush could still be picking up delegates in earlier contests and a win in WTA Florida would land him a big delegate prize and give the media a story about the campaign turning.