General Discussion

He could stroke out and kick it or become a vegetable.

He could let an underlying (Vance, Rubio, etc.) run and if they lose, try to deny the transfer of power to the Democratic winner a la 2020 and attempt to just stay in power indefinitely.

He could try to push some extra-Constitutional avenue and claim he's entitled to a third term and hope that SCOTUS backs him up on it.

He could attempt to claim some sort of national emergency and martial law that would suspend elections in 2028. That one would be interesting.

He could force Don Jr. or Ivanka or even Eric to run in his stead, thus attempting to guarantee that the "President Trump" moniker lives on.

I suppose our fears could all be misguided and he just leaves as he should, regardless of who wins in 2028. But I wouldn't necessarily bet the house on it.

I don't buy "He'll be happy being a kingmaker" at all though.

People said that after he lost in 2020. Trump had no interest in becoming a "kingmaker," as his ego simply wouldn't allow for him to do that. In his eyes, he'll forever be the most qualified person in the world for the job. Claiming that others could be as "good" as him just isn't in his DNA.