Polls are meaningless when analyzing Bush. He's got the most dough, and will get a big boost from Dems crossing over to get him nominated (assuming Hillary continues basically unnoposed).
Florida is the key. Closed primary and winner take all state.
Should the race be tight by the time of the primary a push will be made to vote for RUBIO....therefore pushing Bush out.
That will be next March so a lot can happen between now and then. But should Rubio win Florida the others..Trump, Cruz, Walker and who ever can still be viable. A vote for anyone other than Rubio by Floridians is a vote for Bush....simple numbers game.