Yeah, I agree. I think there's also an argument that it's worth keeping the more experienced characters at the club as an example for the younger players to follow, and as mentors who they can go to for guidance, even if their actual playing time is scaled right back. Obviously salary may have to start reflecting that more scaled back role, but once you're well into your 30s I don't think too many players will be expecting to get the same kind of money they were on at their peak anyway.
The other point worth remembering is that it doesn't have to be a choice between keeping an experienced player at a club and bringing in a younger, long-term option - if you have the available spaces on your squad quota, and the you can afford to do it, then why not do both?