Quoted from Deaconblooze:
He went 11-5 with Matt Cassell. I think he can win with another QB, and I think his ego is such that he'll try it.
I think Belichick is clearly the biggest key to their success. Get him a decent QB with a desire to win and leadership potential, and I don't think they skip a beat.
Man that Cassell horse is beat into the ground pretty good now; comes up every time someone suggests he won't win without Brady.
I'll just suggest that's an extremely small sample size, and point out that 11-5 or not, they didn't even make the playoffs that year. And while people love discussing his one Bradyless season with the Pats, they don't bring up his awful five-year tenure in Cleveland with the likes of Bernie Kosar and Vinny Testaverde.
Plenty of coaches have won with HOF QBs and then won nothing of significance once that player leaves. Brady won't be around forever, and neither will the Pats' dynasty. I think they are linked...sure, Bill can hang around another decade if he really wants to, like Chuck Knoll, but I think the results will be similar.