Rumors are going around that Alito and/or Thomas might retire from the Supreme Court this year. I could easily be wrong about this. But I think the conservative whisper campaign to get them to retire will have about the same level of success as the liberal effort to persuade Ruth Bader Ginsburg to step down in 2013-14. A few thoughts:
He does NOT strike me as a person who dislikes his job. Very much the contrary. Some of the rumors suggest it is actually his family who dislike the DC area, and would prefer to leave. I have no way of knowing if that's true. But his kids are grown, so it would have to be his wife who hates it (if anyone does). Plus, the job of a Supreme Court justice is such that it's not that hard to spend a large part of the year elsewhere, if you prefer (granted, it's more difficult in the Covid era).
There is lots of evidence that Thomas too loves the job, and also that he has a distinctive perspective on a range of issues that he wants to use his SCOTUS seat to promote. I could be wrong. But it's hard for me to imagine he would be happier in some other job or in retirement. Some of his distinctive views (e.g. - on property rights, federalism, etc.) are ones I like a lot. Other ones, not so much (most notably on executive power). But there's no doubt he cares intensely about advancing these ideas.
Alito is 70 and Thomas is 72. Far from highly advanced ages for a SCOTUS justice. Barring some unknown health problem, both can be fairly confident of outlasting 4 or even 8 years of a Biden administration, if they have to. That reduces the likelihood they would resign just to make sure they get replaced by a GOP president.
I like Alito's jurisprudence on some issues (federalism and property rights again!), but have major differences on some others. From my perspective, he's the most problematic current justice on criminal law and freedom of speech, for example. Some of the people on Trump's current list are ones whose jurisprudence I would probably like better (though some others either are not, or I just don't know enough to say). In any case, my prediction could be wrong here. But it's not because I'm blinded by a great preference for Alito over potential replacements.
Yes, there is the precedent of David Souter leaving the Court when he was only 69. But he famously hated both living in DC and the lifestyle of being a SCOTUS justice, and did not seem to enjoy the work. Alito and Thomas seem very different from him in these respects.
It's possible one or both of these justices has some reason to resign I don't know about - a health problem, a family situation, etc. But barring some such eventuality, I would be surprised if either stepped down. Of course, that prediction is worth exactly as much as you just paid for it!