Just think about a "Noctis' suit" mod or even a "control every party member" mod. There are endless and awesome possibilities. ^^
Things like swapping textures is possible with things that can hijack DX calls like TexMod, but the likelihood that anyone is going to create a mod that even changes models let alone controlling party members is something that would require a lot of work and access to a lot of functions that might not even be possible. Depends on how the game is programmed and what sort of access people can dig up IF they manage to even get to that point.
Basically... I wouldn't count on mods ever being a thing for XV. People haven't been able to even mod FFXIII yet, I've seen a content restoration pack for XIII-2, but that's taking content that was available for DLC and making it available for PC. Not only is this far easier than adding new content, but it was also difficult for the person that did these mods to even achieve THIS.