lots of players have talked about new expansion. what it might be
some have good arguments, and others- not so much
most favored is Kul Tiras and South Seas. also showing how Blizzard is experimenting with Argus (Vindicaar is small Capital "Vessel" which can move to any map where you need, and you are bringing your own"capital city" with you all time). and we speculate, that it might mean South Sea expansion, where there might be lots of separated islands and we might move around with our Garrison-like Ship
what if next expansion is UNDER azeroth?
we know Sargeras stabs somehow Azeroth and there will be a hole in it, inside Silithus
there is Qiraji/Silithid infested zone, An'qiraj out there. what if we go down isnide this would, we use some mix of Qiraji udnerground tunnels and canceled Azjol-nerub zone like stuff (remember? in WOTLK we were going to have whole underground zone, called Azjol-nerub. it was scrapped to two dungeons, but later, in Cataclysm we saw Deepholme and vashj'ir as underground/underwater zone tests.)
so what if we go under zose silithid caverns and inside this would and explore some underground places? for sure, under most of Northrend is spread whole azhol-nerub or whatever is left from old Nerubian Empire. during Frozen Throne, anub arak mentions and so do some spiders mention in WOTLK, that nerubian spiders digged up those N'raqi (faceless) monstrosities while they were trying to flee or fight Lich king. and they couldnot handle 2 front war, vs old god forces and LK's undead. and they lost war.
so WHAT IF titans didnot Destroy Black empire?
in Chronicles we can see, in artworks. that Black empire of old gods stretched to whole contiennt.
what if TiTans added some kind of extra Layer of land mass over Azeroth and buried this empire under azeroth's surface?
so far we have seen absolutely nothing left from this huge empire. not even a rubble. only some mentionings and some old artifacts.
or if Black Empire is hidden under Azeroth. like elemental planes or something like that. and we can venture there by going through this Wound?
TL DR
Black Empire is buried beneath Azeroth and from Silithus Wound/Qiraji Tunenls/Azhjol-Nerub we can go down there
and Nyalotha and N'zoth are there as well