Thanks for putting together the speeches. Okay even if it was tryed before I still believe this all leads to an Old God or more specificly Yogg-Saron. Now let me explain why. The Highmountain speech is obviously about beeing controlled or manipulated and who does this more than the Old Gods?
The Stormheim speech is about the kings in graves, the mighty rendered nameless by time and that every king must kneel before death. Let's look at the visions in his encounter. King Lane getting assassinated by Garona, sounds like a king in a grave. Second one is about Deathwing betraying the Aspects by creating the Dragon Soul. As we see in Val'sharahs story line and the defeat of Deathwing the Aspects are now powerless. The third one is about Arthas subduing Bolvar. Obviously no King rules forever and Arthas kneeled before death. In addition Yogg-Saron is the Old God of Death.
The Val'sharah speech talks about the nightmare and how the infinite dark will claim us all. The Old Gods or more specifcly Yogg-Saron is responsible for creating the Emerald Nightmare by corrupting it through the World Tree in Northrend. He calls himself the Lucid Dream and the Monster in your nightmares. He is also one asoziated with the Black Empire as well as the Void some of the most dark things out there.
The Asuna one doesn't really fit this narrativ though. Or atleast i cant find a link. But it still feals so obviously linked. The intro for LEgion when you visit Ulduar shows that the Faceless are still there and Yogg-Saron seems to be active once again. Also for some reason when i fought Yogg-Saron just a few minutes ago I reached 0 Sanity but didnt get controlled which seemed odd.