I think they should add the Emerald Dream raid to TBC. They were developing it in Classic to either add as an endgame raid or a zone. It’s TBC now, so it’s well past when they believed they were going to add it (even though they never did until Legion). Who cares about the details though, they thought about adding it before TBC, so we might as well have it now. I mean, they thought about it. Isn’t that enough?
https://www.youtube.com/watch?v=HKcYAHg8g1o
(though once sunwell is dead and buried long past its lifespan tbh I wouldn’t mind Vanilla+ or TBC+ content like this)