If Nonito wins the championship his next target is to be the undisputed Bantamweight Champion, based on the interview with Tai Lopez Donaire will go on until he becomes the next champion because this is the only thing missing in his career, to become the undisputed champion, so if he wins here he will push for a unification of the title I hope he can still do it at his age, we'll see if father time is still not diminished his power.
https://www.facebook.com/watch?v=648002447275450It's technically not that impossible to do if he really wanted to cement his legacy and be the next undisputed champion in the bantamweight division. But before all of that, he should know and consider some things first like as he age, some factors might change because his body will start to decline specially at his age now where he is not that young anymore. I'd say that he should focus on his upcoming fight first because the outcome will be an indication what to do next.
I think he should not be overlooking Santiago, in fact that's what I read from Nonito, he wanted to win this fight first before they talk about who's next for him. In the face-off, Donaire is the taller guy so that is a plus for him.
Having height advantage throughout his career, we have seen him knocking people out from Darchy to Ouballi before his reign was cut by Inoue. But now Donaire wanted to proved again that he can become a champion. So this is a step for him before we talk about him fighting for undisputed next.