Yeah, my bet is also on multiplayer of some kind. (Which is going to make it pretty boring for me if that's all they show, so I hope there's something else as well like one of the companions we haven't heard in game yet, or Skyhold, or even crafting.)
Okay, you may think that, but I believe if you spend a few moments in deep reflection you'll see that if it was a Multiplayer reveal there are some advantages. Namely that when showing Multiplayer, the experience is defined almost exclusively by core gameplay elements (Combat chiefly, but I wouldn't count out exploration either) so a Multiplayer breakdown would likely give us the most intimate look at core combat features including encounter design, class interaction, geography exploitation.
I doubt that'll convince you it's something to really look forward to, but at least it's a silver lining.