Nightmare/Deeper Dark/Darker Depths/Umbra/(So on) Dimension

An broken dimension accessible from the Ancient City central structure using an item only obtainable from the End. A dimension possibly containing the sculk's origins, and other creepy and dangerous biomes or twisted or glitched versions of biomes that already exist. In an world of permanent night or no sky light. Including grand nonsensical structures and unique loot. (And maybe a new final boss?)

(Just some ideas, in the End, I feel a deeper dark dimension of sorts should be added)

I feel the idea whether it'll be added or not in the future is probably already decided. But, I ask along with others that if it was decided not to be added, to give it another chance and look over it for an update after the End's.