He could serve a third term and probably will attempt to do so, the two term limit could be wiped out with the stroke of a pen and Trump has a record for doing a lot of unprecedented things.
Why are so many so focused on Trump? If the current VP becomes the new P, will it be any better? What about the people behind it all, the ones financing and organizing the whole thing for which Trump is only the public figurehead whose function is to distract and get all the attention?
I think he'd be very likely to be elected if Trump runs as VP on the same ticket and they both publicly state that it would be a 3rd Trump term in all but name.
It's not even a new gambit. Putin did exactly this back in 2008 after doing two terms as president, swapping with his then-prime minister Medvedev for 4 years. Medvedev was also a nobody before becoming the prime minister, and there was absolutely no way he'd be elected if people didn't treat him as a figurehead for 4 more years of Putin's rule.
There is something to be said for, to date, nobody on the right wing in the US managing to even partially recapture Trump's particularly inexplicable brand of charisma. Everybody who has tried has just flamed out (e.g. DeSantis cratering like Wile E. Coyote just looked down).
I think it might take more than a stroke of a pen -- it seems like the easiest legal way would be to bribe the House to elect Trump as Speaker, bribe a pair of Republicans to run and win in 2028 and then in 2029 have each of them resign, promoting Trump back in to office.
The bribing might be costly but people are more than willing to buy Trump's merch.
Just get SCOTUS to rule that the 22nd Amendment only applies to consecutive terms because argle bargle reasons that supersede the language of the amendment.