I am not counting out this team's ability to go to the Super Bowl and win. You never doubt the heart of a champion until they are dead.
But that being said, I think given this year, Brady's obvious decline, the team's very mediocre last third of the season and if they go out early, I think Belichick will have all the ammunition he needs to go to Kraft and convince him to move on from Brady.
And, given Brady had it put into this year's deal that the Pats can't franchise him, that Brady sold his house in the Boston area and didn't get another in the area, Brady's dissatisfaction with not getting a multi year deal last year and some of the rumors telling of his frustration with Belichick and that the team didn't give him any weapons this year, I don't think Tom will be losing any sleep about moving on.
Might be the end of an era in the next week or two.