Copy/pasting my analysis from earlier:
Breaking it down piece-by-piece, there's a lot going on that matches current lore which hadn't been available yet (albeit predictable lore).
I mentioned before, Sylvanas' easy redemption arc, Blizzard loves those.
Tyrande finding her closure with Elune.
Saurfang being dead.
Bolvar playing a role.
Now, all of these things
could have been predicted in July. In a bubble, it's nothing more than flavorful speculation.
However:
Death Knights/Night Warrior Night Elves/Helya+Sylvanas being the three factions in the Shadowlands also perfectly mirrors how 8.3 developments are looking.
That sounds a hell of a lot like the concept art for the Shadowlands leak:
Honestly, this seems like it can go one of three ways:
1. This is the real deal.
2. The person who made the leak got lucky with educated guesses regarding plot, and really lucky this picture corroborated his description of Xiros.
3. The person who made this leak also fabricated the Shadowlands ad, which is why the ad matches Xiros.
3 seems the least likely to me, just because the art is in-line with Blizzard concepts and requires a deeper skillset than just posting random bullshit to 4chan. I also wouldn't expect him to change the name from Xiros to Bastian for no reason.