I might be mistaken about this, but Disney hasn’t released any film on UHD yet, have they?
Assuming they decide to make the plunge someday, perhaps they’ll make a big deal out of it by announcing something exciting like Star Wars to compensate for being well behind the rest of the pack. Again, if I’m not mistaken, they haven’t even been filming (editing?) new movies in 4K as long as the other studios. Is 4K TFA even possible?
Presumably they can render their rotoscopy garbage classic animations ant any resolution they like, if they’re now vector based.
I’m pretty sure TFA’s digital intermediate was 2K. Re: OT on UHD: distributed by 20th C. Fox, who has been pushing UHD very heavily, especially in the sci-fi/action genres. Don’t know how that would work, but I imagine since 20th C. Fox will be printing and distributing, they could release on UHD if Lucasfilm gives the go-ahead. IMO, Fox would be smart to use Star Wars as a format seller (and you’re right, no Disney titles on UHD yet).