Originally Posted by
Qualia
Pretty sure Blizzard has never done that - feel free to give me the quote and source if I somehow missed it (don't remember they did, and a quick Google search gave no result). On the other hand, there are evidences implying that there are other Azeroth with a World Soul.
The original Well of Eternity exist because Azeroth was "wounded" when Aman'thul ripped Y'Shaarj from Azeroth. The Well was pretty much the Azeroth's lifeblood, bled from the scar left behind when Y'Shaarj was torn from the world's crust. Later on, the Well's energy transformed the Night Elves into Night Elves from Dark Troll. The Aspects, and the Dragonflight was transformed from Proto-drake by the Pantheon channeling their powers through the Keepers. We all know about these fact. It should be safe to say that the existence of the Well of Eternity, or the Elves, or the Dragon as we know them can at least implying / hinting that Azeroth has a world soul (I wouldn't say that it's the conclusive proof, but those are that's the only case as far as we know). It had been shown at least a few times that there are AUs with those.
Firstly, in regards to the Legion: they actually did (and probably still do) bother with assaulting / invading alternate Azeroths. In "Illidan", when Vandel received his first vision of the multiverse ("This time he saw not just one universe but a near infinity of them, a complex fractal structure, where new worlds were born each minute from the decisions made a heartbeat before"), he noticed that "In every one of them, the Legion marched triumphant, leaving futures stillborn and presents empty of all life. He saw countless Azeroths, countless Vandels, and countless Khariels, and to every one of them came death". As it said, Vandel saw countless Azeroth being attacked with countless Vandels & Khariels as he knew it (that doesn't mean all those Azeroth were conquered, though). That means not only the Legion did assault alternate Azeroths, those AU Azeroths have Night Elves as well (since there are NEs, there likely was WoE, and a World Soul). It makes sense - the Legion can only put a fragment of their army on Azeroth (due to the restriction of needing portals / summons), it'd be stupid for them to have the rest of their army sit around doing nothing.
Secondly, in War Crimes, Kairoz summoned a number of alternate selves of Azeroth's leaders from their respective alternate universes. Among them, there were Kalecgos as a Dragon (which means the Pantheon in that AU did interact with that AU Azeroth) who knew and experienced Aveena's death (which means there were a Sunwell - and thus, likely a WoE as the Sunwell was created by a Vial of the Well's water). There was Jaina, so human exists there as well. I believe there were mentions of elves among those alternate versions, but I can't quite remember now.
Anyway, based on those, there are alternate Azeroths (countless, even) being invaded by the Legion, has Night Elves, Dragons, and WoE. I'd say that's a good indication that ours isn't the only Azeroth with a World Soul.