Foles would be a good QB to replace Brady if it works out. But I hope Brady plays for another 2-3 yrs. He doesn't need to be elite. If he plays well enough to ride the offense with a good running game and decent passing game, we are in contention as long as he plays. It'll be much better than PM's last year with Denver.
I'd hate for Brady's career to end due to an injury. I want to him to win a superbowl and then retire on his terms, whenever that may be.
Back to topic on BB, he is once in a lifetime coach. He loves every aspect of football there is. Scouting, drafting, coaching, game planning and so on.... Irrespective of when Brady retires, I want BB to coach as long as he can and then sit in the booth upstairs with Ernie (that is to say take a position in some capacity with the team).
I would love for someone like a Josh McDaniels, Sean Payton or Mike Zimmer coach the Pats with BB overseeing everything else.