Dragon Soul and Neltharion Turning to Deathwing
The Dragon Soul was the direct cause why Neltharion's body started to crackup and tear him open. It somehow reflects what happened to the Well of Eternity when the visitors from the future tried to meddle with Dragon Soul acting as a conduit for the WoE portal to Sargeras in the Great Dark Beyond when they try to steal it. Perhaps, it wasn't meant to be stolen after all and what should really happen is let Sargeras enter Azeroth cause no matter what the same thing happened as well.
3 Burning Legion Invasions. 3 times that "her" is going to die.
You are correct, the Demon Soul/Dragon Soul was always involved,directly or indirectly.
There is always this "time traveler visitor" from the future who is always being sent back to the same Event. The War of the An ient, the Well of Eternity and the Great Sundering a succesion of three events.
You are correct that was the exact point in time when N'Zoth finally made his presence felt and right exactly to the person who is directly involved which is Azshara. Unnecessary coincidence? I think it's not.
So Great Sundering ==Azshara scene-nematics.
This is exactly what Blizzard' WoW cinematic was referring to 10k years have passed. The same instance or event horizon in the Azshara Warbringers, Emperor Shao hao turning to mist and Suramar ttapping thenselves in a bubble.