I watched it with the sound off…not quite sure what I was supposed to see?
If you didn't play DA2 (or don't remember anything about it) you would have no idea what they are showing. If you had sound up, you'll have heard a very important DA:I character said something that sound quite a bit like something said toward the very end of Trespasser.
That teaser gives lots of ammo to an old theory too (or two now that I think of it).
Oh and there was rumors a few days ago that the game is ~3 years away so it can released on the next consoles.