I don't see them ever doing a big overhaul, and have it kind of like WoW where certain thing are updated and older assets aren't. For example, I could see them updating character models (textures, quality), but not low level zones. New effects, etc.

It's doubtful they would actually add third clans, those would be effectively a new race. I do see them adding more options if possible like tattoos, faces, features, and facepaint. That is the extent I could see them go with it. Definitely not body sizes, rather types.