OK, here's my Hot Take. We'll see how well it ages soon enough.
I think way too much is being read into the morning after press conference, going both ways. He didn't commit to giving up the GM duties in return for keeping his job, or anything remotely like that. He committed to absolutely nothing but a general willingness to work with everybody to make the team work better, which can mean literally anything, or nothing. Conversely, there was no "shot across the bow" other than him making it clear that he wants to keep his job, which isn't exactly a shocker. "If you want to fire me, fire me, but I'm not pretending I was actually quitting anyway" isn't some crazy stance for him to take.
I don't expect Belichick to stay on with diminished responsibility. He might promise to clean house around him on a bigger scale, bring in new personnel guys and build a bigger/better coaching staff, but ultimately he's either going to be at the top of the football pyramid, or he's leaving. People are understating what a major sea-change it would represent for a guy who became the GOAT coach precisely by being an all-controlling Emperor Napoleon of football to stop and say, "Actually, I need to divest myself of the draft and free agency and offensive staff decisions because I can't cut it anymore in multiple facets of being a head of football ops." I can see him doing that after leaving and taking a year or two off and reflecting on Life, the Universe and Everything, but not now.
