When it comes to TomBrady's impending free agency (if he gets there; I still don't think he will), there are only two recent comparables in the NFL: PeytonManning and BrettFavre. Other than that, it's pretty much uncharted territory when it comes to aging, established franchise quarterbacks.
So it would be very much in Brady and agent DonYee's interest to revisit the lessons learned during those transitions and apply them to Brady.
Probably the two biggest takeaways from Manning and Favre had to do with areas that will be of importance to Brady: Manning's selection process, and Favre's power play.
But if Brady has plans of using their playbook, he may end up out of options and facing retirement.