I thought for sure we'd get a concrete answer as to where Dawnguard will take place. Did I miss something or is this still unclear? I'd like to know if its a new island, a new realm, or in the existing world.

Existing world. However, there is a new place called Soul Cairn or something like that.

This kind of svcks to be honest. I was hoping for a new, large area to explore. Oh, well. The content looks amazing. I wonder if we'll get a true expansion.

We don't know of where the entire DLC will take place. But Soul Cairn is confirmed.

If you watch the trailer it shows you a quick clip of a map. I assume this is the map playing field but it looks remarkably similar to the area of Solitude all the way down to Markarth. But yeah, Soul Cairn is confirmed.

You know they say existing world but in the trailers but either castle would take up a good deal of space and in the trailer we see wilderness I don't recognize. Its possible by existing world they mean you won't enter a different map area like the fallout DLC but the existing map area will expand.