If they trade him, I don't think they would get a comp pick, just whatever they get in the trade. I don't know this for a fact, but wouldn't make sense for them to trade him and still get a comp pick.
They didn't receive one call about him leading up to the deadline, I can't imagine it would all of a sudden start ringing in the offseason, when free agents and draft is available. I would vote for letting him walk, hope for a comp pick, and use that money on other free agents, or to pay Ben or Conner.