I watched this trailer a couple of times today and thought about what Luke means when he says "It's time for the Jedi to end."
First, this dialogue is all pieced together, so who knows the order it's spoken and what the context is.
Second, if you think about the trouble in the galaxy, it all pretty much stems from the notion of absolute good vs. absolute evil. Dark vs. light. Sith vs. Jedi.
Luke asks Rey what she sees: "The light. The dark. The balance." Luke replies, "It's so much bigger."
Again, pieced together dialogue, but maybe Luke realizes the balance--the gray area, the notion that "there is good and bad in everyone" ("ebony and ivory"...all together now) is where it's at. It's bigger. The middle ground of the Force is the strongest. That to truly have peace in the galaxy, the extremes have to end. No more Sith, no more Jedi. Balance in the Force.
But who the hell knows. Maybe the full line is "It's time for the Jedi to end this war" and he goes and carves up Kylo and Snoke like a Thanksgiving turkey.