I have to go with SFOC with this. Varitek's valute comes from his game calling, preperation, and intelligence.
But as others have said, his offense isn't getting any better, I don't think it's horrible though.
So I'm torn on the situation.
I think the question is would it be worth trading off the experience and intelligence for another bat? Sure you could teach any catcher to call a game, work with pitchers, etc. But I think Varitek goes beyond what's asked of and I think that helps the team a lot.