If only Jason Moloney didn't back out of the supposed mandatory fight against Nonito Donaire for the vacant WBC Bantamweight title, he is the best opponent for Donaire to see if the 40 years old former champion can still dominate the bantamweight division now that Inoue is out of the list.
If Santiago will able to pull an upset against Donaire, then Donaire has no chance to beat other bantamweights.
Although I'm not looking at that upset possibility since in the very first place, Santiago was just being considered as the contender for the WBC Bantamweight title because boxers above him in rankings already have their respective fight schedule.
now that magsayo lost his recent fight, it is up to donaire to raise the flag of the PH again. this will be a good retirement reward if in case he will end up winning this fight. time to call it a day if he will be successful on this one. don't chase anymore belts as he is not getting any younger. enjoy the retirement and if he doesn't want to get out of this sports, he can be a coach to the younger filipino boxers.
Winning this fight will be a good exit for him for sure but that is if Nonito Donaire is indeed looking forward to hang his gloves and retire once the fight ends, most probably he will have an announcement after this fight to clarify his intentions to the sport and to settle the issue whether he will retire or not.
But considering that he will be the winner here and what he have said before, he might claim another title before hanging his gloves. It's really up to him.