The part of the trailer that has me really excited is the last line by look: "It's time for the Jedi... to end"
I think so much can be said about so few words. Taking the trailer as a whole, where I think they are going on that line is that Luke is abandoning the teachings of the Jedi Order because he has realized they have failed the galaxy on numerous occasions. Afterall, it was the rigidity of the Jedi Order that lead to Anakin's fall to the Dark Side and the rise of the Empire.
If you listen closely to the whispered words, right before Rey says "the balance," you can hear a voice whisper "the Bendu." If you haven't been watching Rebels, first off... what's wrong with you? Second, the Bendu is a being that is encountered by Kanaan and is pretty much the personification of the balance between the light and dark.
So if Luke is abandoning the teachings of the Jedi Order that was prominent during the Old Republic, and has gone back to the original teachings of the Jedi before the break down to light and dark Force users, I think we may get a look at Luke as training to use both sides of the Force, and teaching of the balance between them.