Even DeSantis getting the nomination wouldn't make him go away. Trump didn't get into this for party or country, he wants the power, adulation, and most of all, money. Even if he doesn't get the nomination, I think there's a pretty high likelihood of him running as a third party candidate with MTG, He needs to keep the grift going.

The most "plausible" options I've heard for making him step to the side include many forms of bribery: agreeing to pay his legal fees if he gets indicted, letting him continue to hold his rallies and raise money even if DeSantis got the nomination, promising him that he can be the Governor of Florida, kissing his ass for the entirety of the GOP convention as the "Godfather of the Party."

And I still don't see any or all of that combined as doing the trick. He doesn't want to be seen as the King Maker; he wants to be the guy who pardons the turkey on Thanksgiving.