Of course, it depends on whether Romney picks Rubio to be his running mate this time. If he does, and he does an OK job on the campaign trail, then he'll be the early frontrunner for the 2016 nomination, and he'd be foolish to pass on a run in 2016.
Also, when is the Florida senate primary? If Rubio runs for prez, but it's clear by March 2016 that he's not getting the nomination, couldn't he drop out of the presidential race and run for reelection for senate? Couldn't Paul do so as well? Haven't other candidates done that before?
In August. Rubio isn't getting the VP nod this year, he's been quite clear on that. As for candidates dropping out- sure, but Dole in '80 (IIRC) is the last time that happened.
