Ok, now i watched the new trailer again and here is my very own personal imagination for the Episode 7 story: Luke Skywalker in JJ's eyes is as Lucas wanted to tell Mark years ago, that he is gonna be like the old Ben Kenobi, the old generation passing the fire to the new generation. Let's all remember, that the prototype of Lucas Star Wars drafts are of a General Skywalker and a farm boy called Annikin Starkiller !! So i think that Old Luke is now the new Ben Kenobi and he teaches Finn (perhaps and Rey too) the ways of the Force. However Kylo Ren (or whatever is his name) kills Luke in order to make his Force spirit go into the new generation (Finn and Rey), so that Finn after all the trainings could be enough strong to stand into Kylo Ren's way in the forest, as Luke himself did with Vader on ESB. I am not into the idea of Han Solo to be dead, not because i like him or something, but because in this new trailer at the end (after the Falcon was burned) Leia was crying in the arms of ... Han Solo! Also this gives more the real feel of the original prototype of Lucas's SW with the old Luke as a master. The new "Death Star" or whatever it is is very similar to the picture from below and the Sith or perhaps a Knight of Ren is very similar to the so called "knights of ren" we are going to see now, or some sort of Sith or other dark side user.