Thanks for the reply!
I guess I agree with most of what you're saying. Maybe it's better if it's something done by the community, at least as a proof of concept. And yeah, I actually had the same thought about ground textures and the like that are designed for tiling.
I do feel like these techniques have sorta "arrived" visually, at least to the extent that they're a noticeable visual upgrade without excessive noise or need for hand curation. I suggested this specifically after being impressed by the real world results of similar projects for games like Morrowind. Even HL1 isn't bad, I don't think? This is the full video that the still you linked is drawn from, right? Left is stock and right is ESRGAN? I'm not sure how legit this is, but it certainly looks consistent with ESRGAN results I've seen from other games with a similar age. The upscaled side looks way better, to my eyes.
Maybe I can figure it out myself, to test it out? Would that be possible for an individual to do? ESRGAN is open source, and there are guides out there to help newbies use it, and my computer is powerful enough to handle doing the crunching necessary, if I'm willing to let it sit there and work for a long time.
I also know there are already user-made texture mods for CoX, and we now have a mod manager in development to make replacement easier, and there are tools to unpack the textures (not really sure how to repack them). There are even guides like this one: https://wiki.ourodev.com/view/Texture_modding.
I guess the biggest question I have is this: can you even substitute a texture for a higher-resolution one, via the simple replacement that texture mods use? Like is that possible at all? I've been Googling it, and some people say you can't. Those are all super outdated posts, though, and I have no idea what the Homecoming client is capable of.