FL GOP has a deep bench. Question for Sanchez and other Floridians is whether those folks would run for an open Senate seat or stick with guv. I doubt Rubio would run for Nelson's seat - much more likely he switches anyways.
I doubt Rubio would run. I think Putnam wants to be Governor, as does Bondi. The primary between those two will be interesting. Atwater's bid to take over the FAU presidency shows that he is more interested in a cushy job than power, so I don't think he is as likely to enter an already crowded primary.
As for the Senate, look out for future Congresswoman Liz Benequisto. I'd also think about Will Weatherford; he might make a go for the position.