Regardless of what he can do when healthy, the simple fact of the matter is that he's either struggled while healthy down the stretch last year, or he played hurt for like the last month of the season a year ago and is hurt again now. At his age, that kinda stuff becomes a major concern, especially if you're a team that's acquiring him and then paying him as much as he's due to receive. The rumors of trading him for the #1 pick this past offseason were so silly. I can't imagine a team would surrender a top 10 or so pick for him anymore unless they're extremely desperate.
And even if they could, I don't think New Orleans wants to move him anyways. He's the guy that keeps fans showing up to see them play.
They have some good players, and I think you underrate their offensive line (for example, I believe Armstead has rated out as one of the best tackles in the NFL so far this year), but the defense is simply a mess and shows no signs of improving really. I think New Orleans is simply stuck in that 6-8 win range until Brees retires or leaves as a free agent and then they'll hopefully start to rebuild.
Anyways, as a Bucs fan, it'll be interesting to see where they go from here.