Although Parenas was KO by Inoue in just 2 rounds, the reference he is sharing on that article is that Inoue is really good right from the start of his career even before he became a professional boxer. The young Inoue was seen getting the potential to become a known professional boxer in the future and he already achieves that.
Inoue was even tagged as the next Manny Pacquiao of Asia although he's not climbing up the ladder yet to become a pound-for-pound fighter.
I think that will be his journey in the future, he has to fight the best and that includes fighting Casimero, then next is Donaire. If he will beat both of them in a convincing passion, then there's no reason to stay, he has to climb and face champions on a higher weight level.
And he should have the charisma of Manny Pacquiao as well to be able to set his foot on US soil. The problem is that there are not many US boxers in his weight class, mostly Asians and Mexicans, so it's hard to carve a name like Manny.
So I agree that he need to go up one weight classes in the future and continue to win against big names in the US.