Simon Galley, an Ilford/Harman director, has mentioned over on APUG that the company will be making up orders for various sheet film sizes next month. It was originally billed as an opportunity to get HP5+ and FP4+ in ULF sizes. But Ilford already plans to do a run of 2x3 film, and I've asked about the availability of 3x4 film. Simon replied that he would look into the "various sizes requested and get some minimum order quantities prepared."
I know there are a lot of people on this site who would be most interested in seeing film available for their cameras in orphaned sizes. If you want to make your views and needs known to Simon, here is the URL to the thread over on APUG:
Simon is a regular contributor on APUG, and he and Ilford seem to be going out of their way to understand and meet the needs of film photographers. Hat's off to them.