While I don't agree with them, I'll attempt to play DeSantis's proxy's advocate. Media heads may recognize that Trump is the favorite, but they can also prop up a narrative that it is driving away supporters of "agreeable, non-treasonous" candidates.
Don't show Trump on the campaign. Don't show his impassioned supporters. Document the prolonged fall of Nikki and Ron as the outsized monetary support eventually dries up.
If they treat Trump as a foregone conclusion for candidacy, it will also minimize the significance of the campaign and wins. "It's not newsworthy, nor praiseworthy."
Once the result is effectively final, you place greater importance on his current legal cases or supposed eligibility problems. Keep up the "walls are closing in" angle on Trump as court cases progress. Or if all else fails, plant a totally legit story in October that people would only believe because Orange Man bad.
In this way, the media manufacture a demoralized base, in theory.