So I’ve been considering something ever since we got the short story, The Vow Eternal. Not sure how convinced I am of this, but I thought it’d be interesting to drop here. Sorry if it’s a bit scattered - it’s mostly just a vague connection of loosely connected dots, that being the main reason I’m just kinda dropping it here in case anyone thinks its interesting.
During Cataclysm, we went to the “End Time” - which was an outcome that Nozdormu assures us was not inevitable in the quest “Murozond”; that said, this was an outcome that Murozond had personally attempted to strive for.
In exact quotes “The “End Time,” I once called this place. I had not seen, by then; I did not know. You hope to… what? Stop me, here? Change the fate I worked so tirelessly to weave?”
Well - I was thinking, the Void views all possible truths as valid. Is it possible that we may find ourselves here once again?
While Deathwing and the Old Gods are dead, “The Vow Eternal” brings up Wrathion’s fear of becoming like his father - similarly, the first boss of Ny’Alotha takes the form of a Wrathion who underwent a very similar fate.
Additionally, take note of the bosses of the End Time dungeon. Baine, Jaina, Sylvanas, and Tyrande. If there was a great time for any of those four characters to end up dying, it would’ve been during either Battle for Azeroth or Shadowlands.
It’s worth noting that for all of the emphasis this patch placed on the Hour of Twilight as we saw it during the Hour of Twilight dungeon and Dragon Soul raid, End Time lacks the minions of the Old Gods that we saw outside of Wyrmrest in the present.
Similarly, something of note regarding the Hour of Twilight as a concept is that this isn’t some random idea that N’Zoth just decided would be on his to-do list that day. According to Chronicle Vol. 2, the Pale Orcs of Draenor were aware of the Hour of Twilight after receiving whispers from the Void, with this being defined as a time when shadow would envelop the universe and snuff out all life in existence.
With this also in mind - I think it’s worth noting the surge in mentions of Renilash throughout this expansion. Given the potentially apocalyptic nature of the event, it may be connected to the Void’s prophecy of the Hour of Twilight.
tl;dr - There might be a chance that the concepts brought up in patch 4.3, those being the End Time dungeon and the Hour of Twilight as an idea, may return in a re-contextualized form at some point in the future.