So I've been thinking about the mysterious process that Noro and Kanae went through to make them what they are. Eto was the only one who was capable of this feat and she's been taken out of the picture (for now, at least) so it does look like this process won't get any further elaboration. It's weird that she didn't make more Noros. Barring any unknown emotional or physical reason, rom what we've seen it doesn't look like it has any negative drawbacks to Eto, and she's able to control these mutant ghouls easily enough. Having an army of Noros, or at least some more than two, would have given her a strong advantage. It's certainly a better alternative than Kanou's half ghoul soldiers.