I would love to see Inoue taking on against Casimero, not just because of the hype that Casimero brought to make their fight happen but because they of equal footing i guess. And if this fight happens, there would be a KO to be expected. I think Donaire is just too old and slow compared to Inoue nor Casimero.
You have a point mate but "too slow" might not be an appropriate description of Donaire as of the moment, he may lose a step but still not too slow as he could still do some damage to anyone including Inoue if his patented left hook land flush on anyone's chin.
I do think that this rematch would not happen or it may take some time to realize as fans wanted the Casimero vs Inoue fight because of the way the former selling that fight.