I could see Bryce Brown, Deonte Thompson, Goodwin and Hogan being "dangled" in trade offers. Coaches have a pretty good idea at this point who is going to make the team. Why not try to get something for them now?
Why wouldn't other teams just wait until they were released? Well, as other posters have eluded to, these players would have to be awarded to teams through waivers. No guarantees. I could see some trades happening.