Gaballo will get a better deal if he upset Donaire the champion here. But if Donaire wins, there's nothing that would change because people are expecting that he will beat his challenger and Donaire will then focus on his main goal which is to fight Inoue. Most probably if we will see Inoue vs Donaire II next year, we might also see Inoue vs Casimero if Inoue will again succeed against Donaire.
I agree, this is just another hurdle for Donaire's quest for the unified belt and he should train hard and not take this for granted so that his plan of unifying the belts with Inoue or Casimero will materialize in the future.
For Gaballo, this is his ticket to fame and he would do everything to upset Donaire.