Very cool trailer with a lot to speculate on. I had some thoughts on a few key scenes.

The scene where Alphinaud, Shadowhunter, and his retinue encounter the decimated camp: The scene begins as Zenos explains that the Populares "no longer present an obstacle." I figure that on this side of the MSQ Shadowhunter was planning to rendezvous with a rebel Garlean force just outside The Burn, but they were put down before the two groups could meet. As to what wiped out the camp it seems very mysterious as the camp itself is relatively intact while its residents are all deceased. Poison of some sort, perhaps?

Also for the scenes later in the Leaders' Conference, it seems as though it is the WoL, Alisaie, and Y'shtola who are being affected by whatever is distorting the WoL's point-of-view. We cannot see Thancred to be sure if he is also experiencing the same. I have a feeling that this event might be direct contact from Zodiark through the Echo. Consider that the scenes where we see the WoL from a third person perspective seem very similar to scenes with Hydaelyn, except for the altered tone and the distinct lack of stars in the background.