Quote Originally Posted by Kaoru_Nagisa View Post
Considering the possible unlock quest is taken from a dwarf in Tomra and sends you to investigate a "mysterious machina-filled ruin" which you aren't yet allowed in, it's more than likely to take place on the First. The dwarf siblings from that questline can be seen in some of the promotional images they showed of the raid in the LL.

Plus there's so much tongue-in-cheek about it being something grand we need to wait on, if it's anything besides Dark Apocalypse, I'd be very surprised.
One of the Tomra dwarves refers to it as a "Grand and utterly nonsensical adventure", which sounds like something Yoko Taro would say about his work.