Well obviously it's a session zero thing. "Hey, I'm thinking about running a multi-generational game, which means that at some point, your character will be retired post-time skip if you're a member of a younger-lived race, and you'll (hopefully) play descendants or relatives of your previous character."
You can then say "yeah uh, I don't want to keep replacing my character with new ones, even if they are just identical sons and grandsons to the original." You can either then convince the GM to scrap the idea, find another game, or play something potentially very long-lived, if allowed.