irst, let's temper your enthusiasm on Stephen Jackson. There is a reason he is not in the league. RB's, at his age, who have taken significant pounding, generally do not succeed. Of all positions, you don't want age at running back. Young man's spot. Sure, there are exceptions, but I don't think Jackson is one of them. You are not getting the Stephen Jackson of 2005-2012 with the Rams. You are getting the really old Stephen Jackson of 2013-2014 with the Falcons, which was mediocre to poor.
Secondly, of your proposed "6 headed monster", let's reduce that to a "two headed monster" of Gronk and Edelman. NONE of the other players are causing defensive coordinators to loose sleep. Amendola, Lafell, Hankerson and Harvin are decent NFL players, but not guys you are building a team around. Was Deion Lewis a nice complementary piece for all of 7 games? I guess. But besides a few highlight runs of making guys miss, what did he accomplish? He wasn't a 100 yard rusher nor receiver in any game, so I am not sure what all the buzz is about. Plus he's coming off a major injury. I wouldn't pencil him in for stardom in 2016. The Patriots can find another "Deion Lewis" to fill the role.
So why have the Patriots dominated the football landscape since 2001? Brady and Belichick. Period. Brady is an immortal, all time great, who has shown no signs (even at age 37) of being anything other than an elite QB. Whereas Peyton's body has broken down, Brady's has not.
Belichick is the best coach in the game. And it's not even close. He has the uncanny ability to take away the opponents strength and he is brilliant at adjusting throughout the game. The Pats always seem to correct any first half problems and that's a testament to Belichick's brilliance. All you have to know is Belichick won 11 (hard to imagine) games with Matt Cassel as his QB...so if that doesn't speak to his coaching acumen, nothing else will.
Listen the Pat's will take a significant downturn when those guys (particularly Brady) step down. Father time catches up to all players and franchises. They've had a great run, especially in this era of free agency and where it seems teams go from bad to good to bad to good every other season. The Pats have been the model franchise (on the field) these past 15 years and that is strictly due to Brady/Belichick.
May the football Gods shine brightly on the Black and Gol