Bill Belichick is on the (very) short list of best coaches in the history of the NFL and he is in no jeopardy of losing his job as the head coach of the New England Patriots. However, a recent piece (focusing on Tom Brady) from Tom Junod and Seth Wickersham of ESPN includes a very interesting tidbit of information on Belichick and that could speak to an earlier exit from Foxboro than some would imagine.
In short, the piece cites "friends" of Belichick's that see his run lasting only through 2019 or 2020.
No one knows how much longer he'll coach, but his friends give him two or three more years, enough to ensure that his two sons, Stephen and Brian, both Patriots assistants, are secure, and possibly long enough to establish a truly dynastic succession.
It isn't a shock to think Belichick would at least consider retiring, if only because he is 65 years old. Beyond that, Brady can't play forever (no matter what he might think) and it is almost inconceivable to picture Belichick presiding over some sort of rebuild with a new quarterback and direction in New England.
At the moment, Belichick sits atop the all-time NFL list in various categories including Super Bowl wins and playoff wins, leaving no doubt about his Hall of Fame career on the sideline. It isn't a lock that he'll hang it up soon but, when this kind of information begins to sneak out, it could be something to monitor in the near future.