I really don't see Horton being traded due to his NTC and his worth to the team, but just to throw it out there... what if Nate sees the writing on the wall with Iginla taking his spot, Iginla possibly signing a contract extension and his impeding UFA status and decides that he wants to move on? Again, I very much doubt this scenario plays out.
I think Caron and/or Peverley might be on their way out.