There is a reason Rubio chose to run for President rather than for reelection. He is hated by FL Reps for his betrayal with the Gang of 8. Rubio would have been primaried and he would have lost.
If that doesn't sink Rubio in the primary, he'll lose his Senate seat in the general thanks to his record of non-attendance and general lack of any achievements as a Senator. So unless the RNC manages to shove him through as the GOP Presidential nominee in a brokered convention, Rubio will deservedly fade from the political scene in a couple of years like the empty suit Flavor of the Month that he's been.