How would you feel about large territories in the game world being controlled completely by player created alliances (guilds). There could be areas that only guilds from one alliance can compete for and some that all guilds in the game world can compete for. For those that know of EVE or have played it, it would be like the Null Sec zones.
Guild would control part of the profits from NPC stores, charge fees for entrance into an ore rich mine. Hire guard NPCs to help protect it from an assault by another guild that attempts to take the area for themselves.
this vid really got me thinking about something like this being in ESO http://www.youtube.com/watch?v=nvK8fua6O64
i know we already have something like this in pvp, but this would be more about creating sandbox content for the game rather than pvp