Correction:
He would have been the front runner in 2028, but he has played the fool in 2024 and has very likely dashed his political future much like Rubio and Cruz did in 2016.
By letting himself be played by the establishment/Uniparty in their attempt to kill Trump, Desantis most likely has swallowed a poison pill that is going to prevent him from ever attaining the White House.
We shall see, but prior to this foolhearty campaign, he was the most obvious heir apparent, now, I really think when the dust settles, Desantis will have damaged his brand to a point where the presidency is never going to be on the table for him.
There is no one else. Again, what makes you think that Trump would be more disciplined this time?