He is definitely playing a Berlusconi in terms of his fear of leaving office and interest in being abroad. Which is why they should refer him to a tribunal for treason; the dead can't run or kill prostitutes.
Even if he were to be pardoned for any federal crimes (which isn't implausible, even without a self-pardon) he seems pretty likely to face criminal charges in New York State and possibly, with the election extortion effort, Georgia, that are not subject to federal pardon.
Prison probably complicates a comeback campaign in 2024. (Also, even without that, he would have neither the outsider ambiguity that help him win in 2016 not the power of incumbency that helped him, but not enough to win, in 2020. He might retain enough influence with the Republican base that if he isn't disabled by legal issues he could win a nomination in 2024, but the general election seems more uphill.)
After the Mueller report was completed ignored by, well everyone really, I have no confidence that he's going to ever be charged with anything. Happy and hoping to be proved wrong.
There is actually some good evidence for this. Balance and motor control issues (two-handed water drinking, weird stance, the “very steep” ramp thing, later covering the ramp to navy ship), body jerking, slurred speech, lack of impulse control and empathy, etc.
The surprise Walter Reed visit was questionable, and the fact that he was administered a cognitive test only given to those with suspected dementia—then bragged about his results and claimed it was a difficult test—only add fuel to the speculation.
EDIT: Not claiming authority here or that others should conclude what I have, especially since I don’t have the time to reference all the things that convinced me.