Dem prez: DeSantis +9
Trump reelected: DeSantis +4
Dems might be locked out from FL Gov Mansion up until 2030 or beyond, because 2026 is most likely a Dem midterm regardless of how 2020 goes. TX-Gov could flip earlier. GA certainly will.
I feel like it's virtually impossible for DeSantis to win by more than 2-3%, regardless of the environment, because of Florida's polarized electorate.
Rubio won by 8% in 2016 and Nelson won by 13% in 2012. Bigger victories can happen, and Gillum would almost certainly lose by at least 5, especially given DeSantis' popularity.