Most likely they will fight Donaire first as that would be an easier journey for them, when Inoue beats Donaire, he can also be a unified champion, no difference with fighting and beating Casimero, so maybe the last step would be being a undisputed and that's a fight with Casimero.
Good point! If he happens to beat Donaire the second time around, that will give him the same title, easier opponent with the same title.
Banking money has a lesser risk, compared with fighting a same caliber opponent which your career is at risk. boxers nowadays
are more practical, the handlers are wise and pride is no longer the priority. As long as they can collect big paychecks, it's okay for
them to fight whoever the promoters choose for them.