**Luke isn't the one who says it's time for the Jedi to end -- it's someone else, I just haven't figured it out yet.
**If it IS Luke who says it, then what he means is in order for the Jedi to defeat the Sith/Dark Side, the Jedi need to break free from not going with their emotions during battle and strategic moments. Therefore, the traditional way of the jedi is being abandoned, and he's going to train Rey in the ways of the Gray Jedi (essentially they're force users who don't belong with the light nor the dark side). They're guided by logic AND emotion, and understand the proper balance of the force.
**As you can see in this picture, someone is touching what I believe to be a book of teachings on the Gray Jedi Order
**I doubt Rey is Luke's daughter.
**This one is REALLY far fetched...I think Supreme Leader Snoke is Yoda's old master N'Kata Del Gormo** This one is way too out there, but it'd be interesting if this came to be true