Bob Shanebrook explains how the scanning of the film works at the coating line. It uses an NIR laser beam with 830nm for all sensitized materials. (Making Kodak Film, 2nd Edition, Page 248)
With this scanning equipment, coating imperfections are detected so that affected sections of the master roll can be discarded when being slit and finished. If one looks at the datasheets of EIR or HIE,
it is clear that the wavelength of this laser falls into the spectral sensitivity of those emulsions.
Additionally, the coating and finishing machines will almost certainly use a lot of other off-the-shelf industrial sensors that utilize IR.
As they are coating everything on this one coating machine in B38, this is probably the very practical reason why a new IR film just cannot be produced.
Some photographers even had problems with IR film when used in more modern cameras that also used IR to detect the sprocked holes or the presence of film or whatever. The invisible light exposed the film.
Ilford SFX on the other hand is a film with an extended red sensitivity. The sensitivity curve drops off sharply at about 750nm, just short of where "real" IR would start. At the typical wavelengths used in industrial sensors and Kodak's laser scanner, it
has already dropped to zero. I am sure that Ilford also uses IR sensors and that explains why SFX can be manufactured on those machines.
Conclusion: No real IR film to expect, because the equipment would destroy the film just moments after it had been made.
Edit: typo