he won't want to and he won't be real effective at 40 plus given his style but i could see him possibly needing money and trying to handpick some money grab type fights (like against another old name or something, like Tito was trying to do his last few years)
I see him fighting Pacquiao, thinking that if he wins that fight it will make him hold a claim as the greatest of all time, which is rediculous IMO but that's what I think he thinks. Right now, he probably thinks that's gonna be his last fight.