DeSantis doesn't have any policy wins to his name outside of the FPRE act and the Disney business. Neither of those things are enough to carry someone to the presidency. Even Romney had his healthcare program to hang his hat on.
DeSantis will primary and Trump will run independent, splitting the party.
This is exactly what will happen. Even if Trump doesn't run independent, a large portion of his cultists won't vote for DeSantis because they will feel betrayed by the GOP.
In no future will this happen in the primary. The Nation has been exposed to far more "anti-Trump cultist" rhetoric declaring NeverTrump for years who won't vote for him.