I'd like to see him defend his title a couple of times. There are a couple of up and comers in the weight division, beat them and if they end up being pretty good then it's a good thing to have on your legacy. Then move up to 154 to finish the career out.
He's finally got a name that will draw, his best earning power is now, time to take advantage. I figure 6 -10 more fights before retirement, should be able to get $100 to 200 million or so. Figure 5 more years or so. Just has to watch his speed, if he slows down it's time to quit. With his defensive ability he has not taken much damage, he looked fresh at the end.
Take on Ennis or Ortiz or Stanionas or Thurman in a PPV then maybe a no name in Omaha. Then go to 154 and consolidate the belts to finish the career, he'd have 4 or 5 years, 4 to 8 fights to get it done. If he can win all 4 belts in 3 divisions, it might be something no one could touch forever and go down as an all time GOAT.
But that is kinda at the max and having everything work out. He's 35 and could slow down at anytime and be done. But this is about the best he's looked, it was a masterful performance. Might come down to what is more important risking a loss on an unblemished record or another payday and growing legacy. I hope he goes for it, 5-6 years of focused hard work then retire with well over a hundred million and an all time legacy and enjoy the last 50 years.