Let's not get carried away here. Yes, Lowell had a very valuable season, probably the team's MVP like Papi said. However, Lowell's second halves (except for this year) have been abysmal. However, I think that's because of the adjustments he has made. He now goes to all fields instead of being a dead pull hitter.
I want him to stay, if not for his production then for the reasons Theo mentioned. He's a clubhouse leader and one of the "core members of the organization."
I would feel very uneasy relying on Chris Carter at any point next year. If he takes Hinske's role, then fine, but anything other than that will upset me.