Dungeon you're thinking of is Toto-rak, Lemuria.

Anyway, while it would be nice, probably wouldn't work out all too well... unless they treated it similarly to T11. They could have made it so the Alliances would go down their own paths and defeat their own trash mobs and then group up together again for the boss fights. Atomos Prime (or in general) is what I like the most about WoD.