Hainsey is still in Montreal's organisation and will try to beat Francis Bouillon and Mark Streit for the team's 3rd pairing. He can't go back to the AHL this year without first clearing waivers. If he doesn't have a good enough camp to be in the team's top-7, he'll more than likely be traded. Unless they decide to keep 8 d-men since Dandenault can play both defense and forward.
If he does have a great camp and makes the team, I think he could get 20 points in his rookie season, maybe more if Souray or Markov go down to injuries.