Lean no -- he had to be cajoled into giving up in 2018, and all reports were that he still liked the job and was only willing to go in exchange for concessions like having input on who his successor was.
The more interesting possibility is that Alito might've -- there are occasionally intermittent reports that he's gotten tired of his role and it's probably true that he seriously considered retiring in the summer/fall of 2020; it's possible that he only stuck around to not distract from ACB's confirmation, although the timing doesn't really work and my guess is that this is not true. It's been Alito's career-long dream to overturn Roe and if that became clearly impossible I can see him deciding to just quit, since he's considered just quitting in the past. (My guess is that for the next GOP President -- whether that's Trump or DeSantis or any other figure -- Alito retires in, like, month one. More than anyone else currently on the Court, he's accomplished what he set out to do and he's been ready for some time now for the handover to the next generation.) Whereas Kennedy relished power and attention his whole life.
Hmmmm... but does that mindset continue if he knows he's not the swing vote anymore and (assuming Clinton appointed young liberal replacements for RBG and Breyer in addition to putting a liberal in Scalia's seat) he has no reasonable chance of regaining that status within a decade? Maybe, as being the 6th most liberal or 6th most conservative means your vote can still be decisive in historically memorable cases from time to time (the most notable in recent times would be Roberts in NFIB v. Sebelius), but I'm not sure?
I can't fathom Alito intentionally retiring under a Democratic president. I think the more interesting question is Roberts. He doesn't strike me as someone who would be happy dissenting all the time as part of a conservative rump, and between Kennedy and the 5 liberals, he wouldn't exactly have a lot of negotiating power on this court. He might even think it's institutionally proper for a solidly liberal court to have a liberal CJ?
