Brees may be one of those guys like Favre. They continue to trot out there until they are wheeled off after the trainer holds up three fingers, asks them how many, and their response is "Thursday."
Brees has been noticeably declining for a couple of years now. I understood his thinking coming into this past year, as the Saints were always rallying for one more run. But the salary cap ramifications may finally catch up with them. If he is seriously considering playing, he may find it to be less fun that he was expecting.
I thought Rivers might go down the same path, but he recognized that while his mind still wants to compete, his body has given its all.