Reading through the new Chronicles book and I came across this interesting tidbit: “After vanquishing Sargeras’s avatar, Guardian Aegwynn sought a place to bury the body so that its dark magic would not disturb the world. She settled on the sunken ruins of an ancient night elven temple—which some legends say was built upon an even older structure of mysterious origins.”
I get that random N'Zoth/Old God theories pop up a lot, but I have a hard time seeing what else that even older structure could be if not a Titan facility which very likely could be N'zoth's prison.