Maybe there will be some kind of a DLC (Stone Hearts model: now it is closed, then it will be open) and by its look it reminded me something very similar to Dying Light: unfinished skyscraper, closed area, hmmm.
Right before the doors to that area a couple talk about that place in a way that there are only psychos (a hint to the high level characters?). Maybe something with the roguelike gameplay.
Also maybe it will be Multiplayer or Royal Battle zone. By the way, stadium nearby looks very good for Arena\Royal Battles zone.