The only way it would be added if the dungeon was made from scratch while retaining the same name. The only thing that ever existed for the dungeon was some sprites. There are no remnants of the actual dungeon, meaning it probably never existed in the first place and was purely conceptual. Even the Dreamscape Labyrinth still has a functional (albeit highly unfinished) map, but there's not a trace of the Parasite Den. It would make for a cool October release, though.