I'd imagine it as an instanced open world zone (cross-server functionality).
- Players may enter any instance they wish as long it's not full.
- Party-formation possible inside the instance (no need to form party before entering)
- Flying disabled (to make the zone feel larger and more dangerous).

The area would have a large variety in mob difficulty, and there would be repeatable quests available at certain camps (aimed at various group sizes, from solo to full alliances). These quests would only be available in certain time windows. As long as the quest is available, target enemies will respawn quickly, you sometimes need to search them, but you don't need to wait for spawns, meaning that it's not required to call out to linkshells and wait for 20+ players to show up.