As far as we know this was taken in some Blizzard's conference room and that's about all we know for sure.
We see a Power Point slide in there talking about some WoWx5 plot highlights. WoWx5 should be the next expansion and apparently it doesn't have any name yet, or at least we do not know about it.
Sylvanas the new warchief?!
I honestly did not expect this and I see no real reason why she might become the new warchief. I guess she will play a very important part into Garrosh's defeat. I can't imagine how the Horde is going to react on this decision.
Thrall goes berserk and joins Mal'Ganis?!
Really? What could possibly go so wrong for this to happen? Ok, he is going to lose his newly born son and his wife, but to join Mal'Ganis?! Honestly I don't think having Thrall as an enemy is going to be easy and seeing Thrall fighting against his beloved Horde is really something unbelievable.
New discovered part of Outland
This is really plausible, since Azeroth map is pretty much full now. This is going to be a great experience for players, especially for those who loved Burning Crusade.
Friends withing Burning Legion?
Based on the older expansions we might see a new race and/or class added to the game and apparently it will be a race/class from Burning Legion. What might it be? I really can't think of anything right now.
We'll wait for an official reaction on this and hopefully we wont see a "remove this post" request, like it happened with the MoP box art leak.