DeSantis probably doesn’t have the nerve to run against Trump. The best case scenario for him is that Trump bows out before 2023, most likely due to health or legal problems. Assuming, for purposes of argument, that no such deus ex machina comes to his rescue, what is the best way for DeSantis to nudge Trump away from the table?
The single best thing he can do is govern Florida competently, while insisting repeatedly that Trump is a worthy frontrunner and that he would never run against him. Being as obsequious as possible definitely helps. In the meantime, he can be raising money and creating valuable connections under the guise of running for re-election in 2022.
My suspicion is that Trump will not run again if very early polls show that he could lose in the primary. The key for DeSantis, then, is to leverage the funds and connections he generates during his re-election campaign into strong showings in these polls without looking like he is actually running for anything outside of Florida. That will be tricky, and it would have to be done quietly, but it is possible.