When it comes to experience, I would say that Donaire would definitely dominate the ring, age might caught up to him, but, he would still find a way to show Santiago that he definitely deserved that title. But, if Donaire would be defeated, there is a higher chance that that would be his last battle, I think.

If Donaire would not retire after he is defeated, I think that it would have a hard time getting the title back as his.