The only one I can really see besides the default three is Elder given his young appearance from the comics. Neca did a figure of it even.
For Jungle Hunter it would probably be the 2010 classic but given he was pre-order it wouldn’t make sense to make something a majority of the player base wont be able to access. You could have an unlock for the original helmet or the classic 2010 helmet being accessible but I don’t think you should need armor styles for that.
City Hunter never changes outfit on film unless we’re somehow getting his one armed appearance or a what if scenario where he has a replacement. One armed would conflict with animations unless we just overlook that. He could become a member of the Lost Tribe but then we’d have to figure out which one since all the ones who use the existing body don’t look that different and not all of them have a wrist blade (so Boar would be left out assuming they don’t ignore the lack of blades).
Elder probably could get one given the comics and Neca have represented a younger appearance that’s different enough from what we currently have. It would also be another skin that shows a weapon mounted since his younger appearance has a holster for a smart disk.
The others unless Neca had an alt and they’d been sitting on other designs for the Illfonic originals I’d wager they’d probably be for the original 3 and maybe Elder.