Do you think with the changes and optimizations Bethesda made with the Creation engine that this might be possible this time around?
Considering the story (civil war aspects) and the different clans it would be the perfect setting to have one clan attacking a stronghold of another. It would be awesome to participate in a battle where 30 or so NPC's from one clan attack a fortress of another and you right in the middle of the battle. Suddenly a dragon shows up and everybody is fighting for their lives instead of each other. I can think of a ton of possibilities and story lines to come up with. It would be a modders dream to be able to create something along those lines.
Think the new engine can do it?