Here's the poster:
Here's the question: Where's Luke?
Han's there. So is Leia. Chewbacca. R2-D2. C-3PO.
In the trailers, too, no Luke.
My prediction, which I have been sharing for a while, is that Luke is the Sith. The bad guy in upper left corner of the poster.
I posted it here so if it turns out I was right, I can date it. The final piece for me was in the new trailer, where the Sith is talking to Darth Vader's burnt helmet, "I will finish what you started." The very sort of thing a son would promise his father.