I think the ultimate resolution of this saga is very telling with regard to the SynthesizerV engine itself and Dreamtonics' goals with it as a product.
First of all, to me it's very clear that the goal for KAFU 'The Right Stuff' was far beyond a port and that the intent was to push the envelope and do something new. The 'Right Stuff' demo was so impressive
because it was so truly emblematic of KAF's singing style
and had a distinct sound. I know there are varying perspectives on this, but to me (and throughout perspectives I've observed thru both EN and international communities) SynthesizerV absolutely has a characteristic sound throughout most of its libraries, and the demo was a marked departure from that. Maybe it was just excellent turning or a really good mix, or just how unique KAF's voice is to begin with, but either way, it set a very high expectation.
Piedpiper's post on the matter is the most revealing IMO: "[Synthesizer V's technology] was so amazing that we couldn't launch this time".
SynthesizerV's triumph is the ability for anyone, at any level of skillset, to generate high quality-sounding voices with the product. "Plug and play" covers have always been a source of some discontent within this community, but it's certainly reached a new audience. It must be restated that the reason KAF gave for postponing the product the first time was the public reaction of its similarity to her voice (a repeat of the first time with the CeVIO release). And now after a year of postponement to determine whether or not something could be done to separate KAFU 'Right Stuff' from KAF to an extent that would be acceptable to all parties, nothing has resolved.
I think Dreamtonics wants to preserve their technology's capability of being an intuitive and realistic synthesizer first and foremost. It's pure speculation, but it's likely that a highly experimental product with experimental training data would have sacrificed on quality that Dreamtonics likely needs to maintain to direct public perception of the product. And on the other side of the same coin, we have KAF, who is a vocaloid fan but has clearly created a boundary for how she wants the technology using her voice to be interpreted by users. I would also like to see experimental voices. I think we have stylized and voice acted voices, but nothing experimental. I'm just not sure in who's corporate interest it is to support such a project on a commercial engine.
IMO it will be a long time before we see anything new with KAFU software-wise, if ever, but there is a whole world of extremely talented artists signed to KAMITSUBAKI and the other 4 under VWP are very talented as well, some of which are mega-otaku (looking at isekaijouchou) who might have a different perspective on the internet's tendency to remix, remake, modify, parody, and reinterpret to any extent possible. So the promise to continue the "musical isotopes" could resolve something interesting.
In the end the fan perspective seems to have become one where the incidental creative direction of the "isotopes" as separate voices/characters than their VPs has really taken root, so I think it's worked out for everyone in the end that it happened this way (other than KAMITSUBAKI with money in the hole on development, but who have done the right thing with regard to this product from the beginning.)
KAFU quickly became one of my favorite voices ever so I'm sad that she's not getting a new coat of paint and a new tool to play with, but also fascinated that it has become the first public touchstone for how this technology interacts with the people it directly impacts.