I proposed this earlier in the week as well. Consider what we have. An aging D that can't force turnovers and requires re-tooling across the board. Keisel, Troy, Clark, Taylor will all be gone in the next 2-3 years. Miller as well on the offense.
This is not a team capable of competing, and will need to rebuild in several areas before it is able to compete. Why not trade Ben now when you can get a high pick or two for him? You basically want to hang onto him for the next 5 years on the assumption that the other pieces we need will magically fall into place while he's here?
The window on his championship runs has closed. Don't do what we did with Bradshaw and just hang on for multiple losing seasons hoping he's elite enough to carry the team. It's obvious in how often he turns the ball over that he's not elite. When the D was able to back up his slangin' ways we were able to pull out games. The D is done, flat-lined.
I'd trade him before he gets on the plane from London for a 1st and a 3rd (and maybe a conditional next year, 4th/5th).