If he's decided to retire, for whatever reason, wouldn't it make sense to sell this sort of thing? Like, barring serious reputational issues, why not? You're not doing any work. They do have to pay a different actor to have you grafted onto still right?
I don't really see how you avoid this but consider... who watches Bruce Willis films? How old are they? Even if Bruce Willis's likeness is in movies or ads, there's a pretty clear expiration date (ours) even if they could use his likeness forever.
It seems pretty rational all around. New actors who can stand in for specialty CGI isn't that unusual right? And even if every actor got some kind of computer life extension and de-aging, the public interest in that actor won't last. Certainly the famous actors are being rational that their likeness may well earn more than their present day abilities can handle (including your ability to care about it).
It seems like a limited short term problem until we get to the point where the human-indistinguishable CGI are invented and then people are shoved into the CGI character. I guess sort of. Except what else was Gollum? I have the feeling this is all small scale and overblown. How many people would this really apply to for celebrity status, 50?