Coleman's played 300 NHL games in the regular season, he didn't even break into the league until he was 25-26. I don't see 30 as the magic line where he'll start sucking or that he'll be past his prime. He's really only just entered his prime, gotten better every year, and he's not the tier of player that you're signing for 4+ years anyway.
I understand we all want to cling to the 'youngest team in the league' thing for when we inevitably play like garbage sometimes, but I'm with
@Machinehead in thinking Coleman would be a perfect signing, and I'd spring for an extra million or a third year on a contract (or both) to do it.