He's still gonna be the nominee. I'd give him, at a minimum, 40% of being the next president at this point.
Rubio is exactly the type of candidate who looks great on paper but terrible in reality. These types of candidates fail because they're overly packaged, avoid taking on tough issues, and people see through it. If he somehow ends up being the nominee, how do you think he'll make it to November without a campaign-ending gaffe?
I'm not necessarily disagreeing with any of that but at the same time this is happening too late with too few other palatable and practical alternatives for the establishment and moderate Republicans. Rubio's Iowa success earned him enough capital that he could survive a hit like this and probably another without it knocking him out.