Problem with that is apocalpyse has different meanings to who you speak to. Though generally it does mean the end of man, not sure how Taurens, Night Elves and such will be included if you mean in a quite literal sense, otherwise even then it's just activating judgement day which will have an aftermath.
Compared to 'End of Creation' that literally means there's not even space, there is no aftermath because there's nothing existing to have that affect or effect. With apocalypse there is something afterwards with it being judgement day. Eternal Hell or Heaven for every soul. I guess for WoW it would be everyone is in Shadowlands.
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But they are being curbstomped because basically the head of it all aka Sargeras clearly gives zero fucks anymore.
It's been functioning, successfully taking planets, ending life and more... Has been been built up to self sustain over countless millennia now that Sargeras will automatically underestimate us - not realising that the denizens of Azeroth are empowered by her really (like the Well of Eternity and Night Elves... Not sure if you know about what Illidan, a Night Elf infused with Fel does to Sargeras
). He also continues to look the other way when the Burning Legion clearly are faltering by the scene with sending Aggramar. Sargeras is so focused on his current task with the 'circle almost complete' he's going to watch the moment his Dark Pantheon ring true in completion. And no one, even his own failing army is going to distract him.
And basically not stepping in whatsoever until the Argus fight where we are fucking with his pet project and at the Seat which holds all of his prized militant possessions. On Mythic raid setting admittedly. But even then - the Burning Legion are not worth his time but the Dark Pantheon he's making are. The Titans malformed souls are much better units than the whole of the Burning Legion. Burning Legion are like the expendable pawns on a chessboard - meanwhile Sargeras is making Bishops, Rooks, a Queen and more that will basically trump Burning Legion in power level alone.
And in fact pretty most of his opponents.
The Pantheon already do trump as demonstrated by killing an Old God already and being able to toe to toe with the Void Lords. So being Dark and in his way of thinking is just win-win supreme. It's why he does what he does in Silithus, he's trying to turn Azeroth like he did with Argus. Argus as I said was Sargeras's pet project and he succeeded in malforming his soul thus he is doing the same to the Titan souls he caught and being poked by the Shivarra.
The dude has found something totally better and pawns that even the Void Lords want and Sargeras is getting instead. Sargeras also is trying to get Azeroth in the only way he knows how by basically turning them into complete mentally fucked up messes that Azeroth is in some degree already in, which will give the Void Lords the willies.
See where I'm going with this at least? XD Sadly, Blizzard again made the suggestion subtle so without Sargeras literally saying "fuck Burning Legion I have better", it's just up to observing.