Yeah, we haven't officially seen Luke yet, Leia has only been in the most recent trailer as well. It's interesting because we know Mark Hamill will be in it, but we haven't seen Luke yet. There is a theory that the hand in
this picture is Luke, but that's just speculation. I personally believe that there will be some sort of reveal toward the end of the movie that involves Luke, but beyond that, I'm not very certain. There is speculation that Luke could be evil (which would be a major, major, major development), there is some speculation that one of our new main characters could be a child of Luke (main characters on both sides of the Force), Luke could be estranged from the rest of the major players and there is some mission to find him, we just don't have solid proof of anything yet. The fact we haven't seen him yet does lead me to believe that we are in for some sort of reveal in the 3rd act, almost like a tease for him to play a bigger part in the next movies in the series, but it's all up in the air. Again, I like not knowing at this point, as opposed to going into the movie knowing that x character is Luke's kid or that he's become the new Yoda and is chilling on a deserted planet without anyone. These things are possible, but not certain at this point, and that's part of my excitement.