A lot of people.would probably be watching this just to see Pacman go in the ring again though of coursw with less intensity. Most probably, the stadium would not be filled by hardcore fans of boxings but jusr of enthusiasts. Pacman still has the power punches and speed at his disposal, but DK Yoo is still a formidable opponent that also has a lot power packing in his every punch.
As far as filling the stadium and bringing sits in the table, I think otherwise. It will still be filled with fans of Manny hardcore or casuals fans of boxing. And that's what really separate Manny from the rest, he is a legendary that can really attract fans and boxers alike. But yeah, he will fight with less intensity, not giving his full power as he can knockout his opponent with a single punch.
I think Manny is still good for a few years of exhibition matches that can still be exciting for the public to watch until it is exciting no more.
As long as there are fans that are willing to pay this exhibition match, it will continue. The Paul Brothers and Floyd Mayweather are making huge money. Even those former boxers and MMA fighters as well.