I do think Nomura has bitten off more than he can chew. And I don't think he's going to be able to connect the Verum Rex stuff to the rest of the series in a way that really satisfies me (I'm also concerned about this meta stuff, of it being "unreality").
I'm also wondering how Nomura is going to be able to tie Verum Rex to KH. Given the poor reception KH3 received from long-time fans who were less than happy about Nomura's treatment of non-Sora characters, I don't think Nomura has a lot of room to err if he wants to keep KH going. Not everyone is going to put up with Sora forever, especially if it comes at the expense of fleshing out other characters who could use it.
I wish he would have made it its own KH spinoff series instead.
This is part of Nomura's problem when it comes to the KH series:
everything has to be tied to Sora in some way, or it's just not Kingdom Hearts (TM).
Could Nomura have made the Versus plot ideas into its own spin-off series? Sure.
Will he? Unlikely, because a "spinoff series" won't be part of the "main series" and the main series is all about Sora.
But what has me most concerned is the character writing. KH's character writing has never been the greatest thing in the world... but it still used to be better than it is now. Most knew characters introduced are pretty much cardboard, as I said above. I feel this started with BbS some (though note that I'm not saying those characters are cardboard), where Nomura decided he didn't need to flesh out Terra and Aqua or Ven (though that's somewhat being done now) as much as he used to the older characters, and then KHUX saw that idea and ran with it. And I don't even think it's because the KHUX stuff isn't where the characters are supposed to truly be revealed, but KHIV is or whatever. I just think Nomura and the team have gotten lazy when it comes to getting in the minds of KH characters. It's like how everyone jumped on the Strelitzia wagon because she was the first character in ages to actually feel like one: to have wishes and goals and an actual personality. But they only did that so you'd care when she got killed off. And that is just... worrisome. It's clear that they still can write good characters if they feel like it, they just don't want to.
See, it's "games" like BBS and
x[chi] where Nomura's desire to tie everything together and make them all about Sora becomes a problem: he has to sacrifice characterization to ensure minimal Kudzu Plot. IMHO, BBS and
x[chi] would have been fine as their own stand-alone series had Nomura just left Sora and the rest out of it: Nomura would have had the freedom to focus on these characters and plots without the added worry of "How do I tie this into Sora's story?" Like Final Fantasy, which has multiple different "series" based within their own continuity, KH could have kept BBS and
[x]chi their own series and fans would have been fine with that. Instead Nomura, as he always does, felt the need to tie everything back to Sora. So he just had to contrive a couple of scenes to tie these two completely different 'series' together with the main KH series because Sora.
Look at how convoluted these games (BBS and [x]chi) became after Nomura tied them to the main series: each adding their own cast of characters to the bloated main cast. This is especially bad in [x]chi AKA UX. I don't think very many people were 'clamoring' for the Somebodies of the Nobodies to appear and be given any significance within the story, but Nomura had to tie the Nobodies from the main plot to UX after Xemnas (Nomura) revealed their "ancient keyblade secret", meaning even more time travel and "plot twists." Suddenly there was less time to focus on developing these characters and more focus had to be put on tying these plots together.
I never thought I'd be in this boat--because I used to be annoyed at other fans who did this back in the day--but now... if a KH story isn't about Sora and the gang, I'm sort of not interested. Because at least I can still care about those characters, from a time when they actually were written okay (though KHIII surprised me, with how Sora was the best he'd been in a long time--where he actually learned stuff and grew--and was funny really for the first time ever and stuff. But that just shows me that Nomura will only do that for the pre-established characters, it would seem.).
I'm honestly becoming less interested in Sora and Riku the longer the series goes on. Sora already feels like he's been developed enough to not need anymore attention--same with Riku. At this point, all they're doing is taking away screentime from characters that could deserve it--like Kairi or Aqua.
And I'm someone who actually loved/loves how convoluted the story is, because I like trying to piece it together. But I think Nomura has sacrificed good story and character writing all for the sake of being "shocking", which isn't good.
IMHO, Nomura has made more of a trade-off between the plot and the characters: the plot is getting more focus while the characters are getting less developed the more the series goes on. I'm still wary of how the "next" KH game is going to play out in terms of character development--KH3 and MoM haven't left very positive results in terms of showing Nomura has learned his lesson: instead of fleshing out the characters in MoM or Re:Mind, he focused on filling in some plotholes and throwing in some bits of character development here and there.