First off, I apologize if anyone has written anyrhing like this before. I took some time and I couldn't find anything that was similar to this. I will take some time to explain what this theory is. It's main intention is not to spoil details of the film's plot, rather, it is meant to try and offer a possibility of the structure of the film's plot. Here is what I think the narrative structure of The Force Awakens will be:
Instead of the film following only one storyline, it will follow two, namely, Rey, Finn, Poe, Han, all those characters, while the second storyline will follow Luke, and what has happened to him over the course of the last thirty years. Now, at first glance this seems kinda dumb, but look at what we know.
1). (Potential Spoiler) Several merchandise and media outlets have revealed that Rey and Finn are searching for Luke.
2). Mark Hamill, the actor who portrays Luke in The Force Awakens, recieves second billing on the film's official poster. SECOND BILLING, PEOPLE! Wouldn't it not make sense if Luke's only appearance was at the end of the movie?
As you see, the above kinda makes it clear that Luke is of major importance to the film's story. Honestly, I really have my fingers crossed that he has become a Jedi Master by this time. However he turns out, Luke is going to be what is called a McGuffin, a story device that is the ultimate goal for the protagonists, in this case Rey and Finn. I think that much of the film will show Luke, wherever he is at, and how and what he has been doing these past 30 years. Thank you for reading this, goodbye.