I don't see them trading either Seidenberg (who they just re-upped) or Boychuk, their number 2 and 3 defenseman respectively, when they are trying to win now. McQuaid would make more sense, but he is making 1.5 mil, and what are you going to get in return? I think having him for the depth and experience he brings your team is more valuable than the third line player he would likely fetch in a trade.
You are going to need 8-9 NHL-caliber defenseman to get through a deep playoff run. Even with Bart and Krug in the system last season, Chia still traded for Redden at the deadline. Turns out, we needed just about every last defenseman we had at some point. Defenseman get hurt. It is a physically demanding position to play. Right now, you have 8 NHL-caliber defenseman that have all contributed this season, and I wouldn't be looking to trade any of them unless a glaring hole opens elsewhere on this team.