If there's no problem happen with past promotion who handled Casimero at that time then maybe we see that fight happen. But I guess there are forces stopping to make that fight happen that's why now we rarely see him getting a big match. Also I don't think there's still a chance for Inoue and Casimero fight would really happen. The monster is already on top of his career and provably that they won't go down on Casimero's level. Maybe they would prepare to go up and chase for more achievements rather than thinking about fighting Casimero.
I don't think, with the exception of Donaire, Inoue has fought a former three division titlist and undefeated for the last 7 years, only Casimero has that record; he is actually far better than those he fought, and Casimero has beaten over 6 former champions. Forget the record. How about the mocking and the insult he's been getting from Casimero These should be enough to ask his promoters to make a deal, but no, his promoters think that Casimero has a chance to stop Inoue's track, so they just bear the insult and the mocking rather than fight Casimero.
Fans want this fight to happen but I guess Inoue's camp is not interested anymore in Casimero. But let see if Casimero get a big win against Sanchez maybe the fans call out will spark some interest to make this fight to happen. Maybe promoters would smell some huge money for this fight then think about try to create a deal to possibly set up this match up.
Its not that they are are not interested but they think that Casimero is capable of knocking out Inoue, They saw it on the Tete fight, Casimero is the underdog on that fight but he changed the course of the fight with one punch, Casimero loves to mock his opponents when he knocks them down and that will be the end
of Inoue's like what happened to Tete who resorted to drugs to win his succeeding fights, that fight literally ended Tete's Career.
So we can conclude Casimero is a different fighter, very different from all Inoue fought.