I was there speaking w/ Keith on those large format panels, so I have a little bit of insight.
This isn't about any particular emulsion or subscribing to retailers or anything like that. What it's about is Keith offering a place to bring people in the LF and ULF community together for film orders so we as a group can get emulsions we're interested in in large sizes. It's just a matter of having enough people, or big enough orders to make it happen.
To clarify: if there's a desire for it, Keith can get any emulsion Kodak makes cut to any size. He currently is selling 8x20 and 20x24 cameras, and I also know there's a lot of people shooting 11x14 that he works closely w/. They all need film. I'd expect some runs of 11x14 and 8x10 in the new Portra since I imagine there are a lot of fine art and portrait guys out there that will be looking for it.
I'd encourage anyway interested to just get in touch w/ the guys at Canham about it. Imo, what Keith and Kodak are doing is great. There are more people who want this film out there than many of us know, and Keith is trying to make us aware of each other so we can get together. And Kodak is more than enthusiastic to retool their lines to fulfill the orders. So despite the rable rable on the internets and etc, I think there's more love and dedication and thought going into the materials we use from people like Keith and guys at Kodak than most people suspect.
Regardless of my opinion, hope this helps clarify some of the specifics.