He can match with other boxers that he haven't taken yet and I guess that's where he should focused first before aiming for someone like Inoue again.
A rematch with Inoue is not even close to happening. The time Nonito Donaire will take a shot again at the Bantamweight title, Inoue might be at the point now where he challenges boxers in a much upper-weight division (probably at 122 lbs up) which is possibly his next task if he will become an undisputed champion on the bantamweight.
That is a huge possibility, despite that possibility, I am still wondering if the Inoue and Casimero fight happened, who would have won? Is there a chance for Casimero to win that fight? I heard from some Youtube blogger that Donaire is evading Casimero because the latter has a huge possibility to beat Donaire.
A Donaire vs Casimoer fight will be exciting to see though, no doubt about that. But I think they only have a slight chance that they will share the same ring because Donaire is planning to move to super flyweight which is a lower weight class whereas Casimero might move to the upper weight class somewhere in super bantamweight or featherweight because we know that he's struggling in reducing his weights, what more if he will chase Donaire in super flyweight.
I am not fond of watching two Filipino boxers fighting each other, besides I think Casimero will have trouble with the weight if he chases Donaire to Super Flyweight Division. The fight between the two is highly unlikely to happen unless they have a match before they move to different weight division.