I think the emerald dream would make a good mid-tier raid but not a full expansion. If ever we have an expansion where we deal with the Naga once and for all then toss that bad boy in there for mid-tier and then Az'shara/N'zoth. It only makes sense as N'zoth is considered to be the one corrupting the emerald dream and under the sea corrupting the Naga. As for an entire expansion? No, theres not enough 'life' in the emeral dream including quest givers, animals to make poop collection quests or critters to throw mercilessly into battle ala thunderdome, two squirrels enter! One squirrel leaves!