I agree that's a pretty solid number for service life, but I assume there would be some holdovers.
Thinking of military aircraft, most workhorse attack/fighter aircraft are platforms that have been in service 40 to 50 years, and are still in production. Updated, certainly, but still that platform. Others have come and gone, but the good ones prove useful for a long time.
If that applies to jets, I'd assume a good starship design could be expected to serve a century, with periodic updates. Apples to oranges, maybe, but it's how I frame it in my mind.