At some point the Packers are going to fix their offensive line problems, so Jennings value will rebound. Forte would be the one I would be worried about. The Bears D is struggling, so Cutler has to spend more time trying to bail the team out which has not served the Bears very well. The Bears o-line is weak also, and I'm not sure they are in a position to fix it sooner rather than later.
On the flip side, by the middle of next year, D-Will and Stewart could be in a 50-50 time share on a terrible Carolina team. I would get value for him now.