Originally Posted by
AnakinFlair
This question has already been answered in Rogue One. Peter Cushing was dead for years, and they brought him back via CGI, MoCap, and a sound alike. And I think Carrie Fisher was still alive at the time when they did the same thing in the same movie to show a young Leia. Heck, we got a younger Luke in The Mandalorian, though in that case Mark Hamil was consulted and did the voice work.
The technology will keep getting better and more refined, and they will keep doing it whenever they need to do it. Heck, I wouldn't be surprised if we get a show in the not-too-distant future featuring Luke, Leia, Chewie, Han and the droids in an adventure set between Episodes 4 and 5, where the big three are MoCap/Cgi creations with sound-alikes doing the voices (they can probably get Mark, but I doubt Harrison would want to do it).