BB has made Kraft a ton of money and helped them become one of the most prestigious Franchises in the NFL with the 6 Lombardi's. He's essentially only had one chance to have a successor after Tom left. Fans thinking you can easily have a guy waiting in the wings to continue the dynasty are being unrealistic. That **** only happens in Madden. He's owed $25M next season and Bob isn't going to pay Bill, fire him and take a chance on a potential Adam Gase, Mike McCoy, Brandon Staley, etc. hire. He's too old to take that chance.
And from a business perspective, it's a horrible look on Bob to fire Bill right now.