Remake or finish an unfinished content. Does not matter which word I use, because the previous development team is laying down a catacomb in the end of Dragon Spine.
https://www.youtube.com/watch?v=fvsv39CycSg
And now I think I answered you too Evito.
But you can still are dreaming about the thought that this is gonna be a brand new raid with brand new bosses. :)
They are laying down years ago beneath desert of Stygia. So this is just a remake an old unfinished content.
There are many unfinished areas in the game if you open your eyes, do not be naive.