Also a good point about Denathrius’ words, and I thought the hole in Zovaal’s chest went without saying here.
Your speculation sounds accurate and could be canon, and it’s also the same as Sargeras’ original lore from Warcraft 3 (he was so traumatized by witnessing the evil of the demons, after a struggle he rejected good and embraced evil, leaving the Titan Pantheon, recruiting an army from across the cosmos and later fighting against his kin).
Should also mention this. Dialog between Thrall and Bolvar after Slyvanas is defeated.
Spoilers
Spoilers
Spoilers
Thrall: We thought the Jailer was coming to slay the Arbiter. But he… absorbed her essence.
Bolvar: As if his power–and the sigil–were his all along.
Jaina: Jailer be damned! He’s got Anduin. No matter where he’s gone, we will find him!
Thrall: Maybe she knows.
Jaina: Yes. Sylvanas said something before she collapsed, but I couldn’t make it out.
Bolvar: My knights will hold her captive here in Oribos. When she awakens, we can begin the interrogation.
Bolvar: For now, we should return to Korthia. Let us hope the Primus can explain the Jailer’s plan…and tell us what must be done to stop him.