I think they might have some news about the x-pac after wod, and i believe they might spoill it next Blizzcon, just because they hinted in recent interviews that they are already working in it, and that they want to ship content faster then ever, which means that we might see 3 patches for WoD, at an average of 3/4months each, at that rate they would deliver next x-pack a year after WoD. That means that next Blizzcon is the best place to present it.