Northern and Central Florida has always been South Alabama.The main reason it was a swing state was that it was a retirement haven primarily for liberal Jews from the Northeast (NY and NYC in particular). They were the core liberal constituency there. Well, those original transplants have been dying off, and their replacements haven't been liberal. It's expensive as hell now in the Jewish-friendly areas and hard to retire to, and lots of people from the Northeast are going to have little interest in relocating to Osceola.
Otherwise, why would we think Florida should be different from any of the other Confederate states?
It is South Florida that has changed so much - in part for the reasons you state and in part because the Latino population (especially the non-Cuban Latino population) has trended more red over the last decade.