So it foreshadowed the wrong information? Not to mention the Makgora cinematic & war campaign conclusion was released less than a month before Blizzcon 2019, where Shadowlands was revealed so those details hardly count.
Okay now use any of that vague information to accurately predict the actual events of Shadowlands. (You can't. And no one did.) (Also half the things you listed weren't from BFA. The entire thread about Odyn's eye & Sylvanas' career wasn't canon until Shadowlands. Odyn's eye is never mentioned in BFA) There are mystery box callouts. They're not substantial: For example, Sylvanas didn't need a conspiracy to become warchief because she was next in line for leadership regardless.I think you all need to understand confirmation bias. There weren't more necromancers in island expeditions than any other creature type. Even so, they have no connection to the Jailer. There's necromancers & undead in every expansion somewhere.