Another Floridian active in politics there who is not putting bets on Crist quitting says there’s consensus on this:

anticipate an escalation in Crist’s smear campaign directed at Rubio, with Crist using surrogates to do his dirty work so as to preserve his “nice guy” image.
Moreover, the relatively early timing of Crist’s announcement that he would not seek re-election as governor prompted other candidates in both parties to jump into that race, so Crist’s “going back” into that race would really create political havoc as well as making it look as though Crist ran from a fight.

Having spent some time with Rubio this week, there’s no question that the candidate and his campaign are expecting just that. The candidate doesn’t seem as worried as he is dismayed because he’s actually a candidate who wants to talk constructively about issues. Regardless, they are expecting what’s likely to come.