I think Caserio is staying put to take over full control when Belichick steps down.
From your mouth to God's ears. I think that Caserio's value to the Patriots is not fully appreciated by many.
I have always thought that the Patriot front office did a really outstanding job of drafting when one takes into account that, because of their unprecedented record of success, they have worse average draft position than any other team, and that is even before Goodell's loathsome stealing of draft picks.
However, IMHO that is not where the Patriots front office REALLY shines. Being an old timer, I remember the first Super Bowl year when BB seemed to have the golden touch when it came to free agents. Then, not so much, and for a number of years it was more mixed, with strikeouts like the Duane Starks move.
Then, in recent years, starting about 2013 or so, it seemed like the Patriots could do no wrong when it came to their poaching of pro talent from other teams. It was absolutely remarkable, with little or no draft capital every year the Patriots would swoop in and poach other teams lightly regarded players (usually on the last year of their contract) and turn then into solid starters. A few times, those players got extended (Branch, Blount, Lewis, Van Noy). Other times they went on to bigger and better things and the Patriots got Compensatory picks worth about the same as what they originally gave up (Hicks, Ayers, Long, Sheard). I think that there is little question that the Patriots have handled these transactions better than any other team for the last 4 years of so.
At one point I thought it was Michael Lombardi who had the golden touch for these type of poaching of other teams pro players, but he is long gone and the success has largely continued (Ealy was an exception), so I can only conclude that the reason for this success is the maturation of Caserio, I think Caserio has become the best in the league at these type of pro (as opposed to college) player evaluations. I think Caserio is more important to the Pats than anyone except BB and TB, I hope we can keep him and have him eventually assume full control.