It's pretty plausible that at the point that Phoenix II needed to be cleared to go for wide coating (or risk missing the available coating window) the yellow masking dye (to take the obvious example) was very close to being ready for incorporation. Once it's incorporated (and any undercuts that will impact the red/ cyan layer), that'll be the point at which anti-halation can be done (as they'll have a more final answer for overall emulsion internal behaviour etc). Once you have a known & good set of couplers and masking couplers, refining the emulsion characteristics (especially in terms of grain/ speed etc) elsewhere becomes much more achievable. I do wonder what the final speed of Phoenix III will be (I'd guess the aim is 200, but I suspect that it might have to be 100 initially).
I do recommend that people listen to the Sunny 16 podcast from Jun 16 2025. The guest is Michelle Parr, who is Harman/Ilford's main digital marketing person. She's the one you interact with if you are on Insta, Facebook etc. So she's no chemical engineer but she does know what's going on. One thing she stated was that Phoenix I was improved incrementally with each batch - so we now know there were several coating runs. Which also gives us an idea that they manufactured and sold a *lot* of it. Phoenix II will be the same. That may explain why some of us found that the Phoenix I we bought on launch day had less of a purple mask on the negatives than later examples. Another thing Michelle said was that the next big iteration (presumably Phoenix III though she didn't state that) might be ready in under a year and that they were very close to implementing the anti-halation.
Now....a Phoenix II type film with orange mask and anti-halation is going to be something that really could be an everyday film. Sure, it's more grainy than anything Kodak offers but in terms of colour, contrast and latitude it's going to behave fairly "normal". I get the impression that both you and I see Phoenix II very much as an intermediate step to another big improvement.
She didn't reveal much more about the roadmap. In the past, Harman have talked about more formats, faster film speeds and so on....once they have achieved their aims to reliably manufacture a competitive 200ISO CN film. BTW, it seems that Phoenix II is much closer to 200ISO than OG Phoenix. Though the one roll I've shot, I did err on the side of caution and mostly that worked out for me.
As for Harman's commitment to B&W, they have the world's most comprehensive line-up of B&W products. Nobody else comes close. There's no plans to change that. R&D though is mostly limited to ensuring all those products remain which sometimes might mean finding a substitute for a chemical that isn't available or practical. Though as Michelle Parr said in that podcast they did launch Kentmere 200 and there will be at least one more B&W launch in 2025. They're not abandoning or even deprioritising their core business. The impression I get is that the R&D on B&W films, paper and chemistry has been at the level it's currently at for a long time. We're not going to get an HP6 or Delta 12800. But we might get another film in sheets. I also look back at Ilford went into administration 20 years ago and at how there was very real concern that we'd lose all these wonderful films and papers....and yet here we are in 2025, not only with all the B&W films still available but with a couple of new ones launched and a genuine move into colour film production.
900nm IR film, I think you've hit the nail squarely on the head as to why nobody is making it. The short shelf life means it would have to be made by a company able to do small batches....and even then, it's viability is dubious.