Blizzard released a teaser for a potential upcoming animated project set in Quel'thalas, and here we examine the trailer to determine exactly what it might be about.
The most obvious piece is the setting, with a very obvious shot of high elves against orcs and trolls in Quel'thalas. What might be less apparent in its quick frames is that the spires of Silvermoon in the background are not their signature red of the modern day, but a distinct blue from their time as high elves. While Silvermoon sported blue spires for most of its existence, it donned its modern colors alongside the shift as a people to be called blood elves, to honor those who had fallen against Arthas and the undead Scourge when he razed the nation to the ground.
Additionally, you can view the looks of a few characters, some more distinct from others. Most obvious is Lor'themar, who sports his modern outfit as well as two blue eyes, indicating again that this takes place before the fall of Quel'thalas at the hands of the Scourge. It was during that invasion that Lor'themar lost his eye, and nearly his life. In the modern day, he and most other blood elves sport not blue eyes, but green and gold ones, reflective of their time using fel magic and the power of the restored Sunwell respectively.
Though not confirmed, the high elven woman in the front is likely Lady Liadrin, the modern Matriarch of the Blood Knights. Prior to becoming the first blood elven paladin, Liadrin was a priestess of Quel'thalas, and adopted daughter to its High Priest. She adventured alongside Lor'themar many times during their days before the fall, as well as alongside Halduron Brightwing, its modern Ranger-General. While also not confirmed, it is possible that one of the elven rangers next to her is Halduron.
Additionally, and rather obviously, the enemy that the elves are facing is not the Scourge or the Void like we would presume