The new Blizzard insider has some nice tid-bits about instance creation and upcoming content (as well as current content). Zul'Gurub, and an interesting resource-centric Battleground, Arathi Basin are mentioned:

The next World of Warcraft content patch will feature two major new areas for exploration and conflict. Zul Gurub is a 20-person, casual high-end raid dungeon, extending World of Warcraft's epic, high-level end-game. Also in the next patch, the dev team is planning to release a brand new Battle Ground - the Arathi Basin - for player-versus-player mayhem. Arathi Basin will be a medium high-end map that will focus on the Horde vs. Alliance resource struggle. Teams will need to capture and hold strategic objectives to gather resources for their side.