In the next patch, patch 108, a plethora of dungeons will be removed and some will return (with 2 new ones) as seen below. There are many things I could say about this change, mostly negative, but I will address the most important one to me here:
Catalepticon Hard mode is, in my opinion, one of the best original dungeons that the Tera devs have created in a long time. To see it leave the active dungeon roster so quickly is a major disappointment. With the way its mechanics are structured, it fits perfectly as a top tier dungeon (with the right balancing). Please bring it back asap!