I have lived in central Massachusetts for more than a decade, and am moving to Connecticut later this month. I've experienced all you have.
The truth is, Brady won't be around forever. And Belichick won't stick around long without Brady, because if Brady retired and the Pats became mediocre, it would prove that the team's success is all due to Brady, not Belichick. So once Brady is gone, I think they will regress to the mean.
The problem is, most Pats fans are only casual football fans when they aren't winning. The Pats used to be what you did to kill time between the Sox being eliminated and pitchers and catchers reporting. Pats fans don't realize that this is special, and that it won't last forever.
If you live in Mass then you do feel my pain. I'm afraid when brady leaves there wont be that big of a drop off. Remember the Cassel year? 11-5. Cassel had bettrer stats then brady did the year he returned. Brady has always had way too much time to throw. thats what has made him great. he has rarely been hit outside of the 2 Giants superbowls and a little this year.
belichick cheats and it isn't going to stop. they are slowly rewriting the rule book to stop him but they can't do that forever. he will do anything it takes to win and probably spends more time at finding ways to bend the rules or outright cheat then anyone.
if they can't fix the oline and brady leaves then things will change but until that happens I'm not holding out hope