Im an avid bonucci critic, and even I think it will be more harmful than good to sell him, specially after this season that he seems to have finally (omg) found what he needed to be a good CB.
Without him, chiello or barza, we are unstable. Barza seems to be getting too injury prone, and Chiello is random. Bonucci has been our only constant in defense.
Selling him now would be a big mistake.