I can understand your concern, UK, but the timing isn't quite right for Jimmy to stay. IIRC Tom's current contract ends after the 2018 season, and I'm convinced that for the next 2 or 3 years, Tom Brady is STILL going to be the best QB that the Pats can put out there. So that's the problem for JG staying. That and I think they like Brissett as that possible transition guy and he's going to be under the Pats control for the next 4 years.
Now the Pats COULD wait another year and keep JG and trade him after next season, like they did with Castle, but THAT is a far more risky move given teams only have to wait a month and he'll be a FA and they have to give up nothing. Plus even if they do manage to trade him, the compensation wouldn't be as high, since the Pats would have less leverage due to the time constraints.
No, UK, dealing him after this season would be ideal (assuming his play remains consistent). The Pats wouldn't be squeezed by low ball offers, and historically QB starved teams vastly overpay for potential QB talent. You just have to look at what the Vikings paid for their new QB. Right now, I would foresee something like a first and 4th in 2017 draft and a 2nd in the 2018.
Imagine the consternation at 354 Park Ave, when Roger has to hand the Lombardi over to Tom Brady in February, and then watch the Pats get a top 5 pick at the end of April. Now THAT would be a dream come true for us all.