Marco Rubio is definitely not going to be the GOP nominee for 2016. Should he stay in and hope for a miracle? Should he stick it out through Florida? Neither. Here's why.
Marco Rubio does have a path to the presidency. It just doesn't cross the finish line in 2016. He's got some image repair to do. Bowing out now would prove he's not an establishment lapdog. It would prove he's not blind to reality. It would prove he's gracious. And it would prove he's willing to put the needs of many on the party (the anti-Trump factions) ahead of himself.
It would give him 4 to 8 years to re-define himself among conservatives. He needs it. The best path for Rubio is to bow out, because it's the best path for his political career and more importantly for the party.