I don't necessarily accept the premise of him fading away but I doubt by then he'll actually still want to go through the same process only to very possibly lose again. The possibility of him dying or being in jail by 2024 is WAY overblown by wishful leftist hacks and isn't likely, so even if the nominee isn't him he'll likely be a critical part of the Republican's outreach and voter turnout operations.
Remember when claiming that he'd try to stay in power illegally was considered something made-up by "leftists hacks".
Did he? He left on January 20th right? If you're referring to the riot on the Capitol, I think you're giving way too much credit to the idiot diehards who weren't serious at all about any kind of "insurrection" (if they were, there would've been an actual plan in place and not mass chaos). I was well aware of the possibility that Trump would throw a tantrum over the results and not accept it. The consequences bear themselves out on Jan 6.
Depends, does he throw a tantrum over mail-in voting? Does he go on Twitter rants in December still bitter about the results? He'll go out in the '30s most likely if that happens but remain in mid-'40s if he concedes properly.