The title of Star Wars: Episode VIII is now Star Wars: The Last Jedi. It's a loaded title, only the third (one per trilogy?) that doesn't have a verb in it. It follows a couple of exact lines of dialogue, as well, that give us some hints as to whom it's referring to (more on that in a moment). It's also interesting to have a title with such finality being the middle chapter of a trilogy - Return and Revenge are titles with finality, too - but they were the last chapters of their respective stories.
So who is the Last Jedi? We'll go over some options - and start with the obvious one. Remember, Jedi can be singular or plural, so the fun part is it could be all of these things.
Obviously, the title is referring to Luke Skywalker in at least some capacity. We have dialogue from two movies to support that, including Star Wars: The Force Awakens.
First, in Return of the Jedi when Yoda was dying, he told Skywalker, "Luke, when gone am I, the last of the Jedi you will be." Then, when Supreme Leader Snoke was addressing BB-8 and the map to Skywalker getting back to the resistance in The Force Awakens, he said, "The droid will soon be delivered to the Resistance, leading them to the last Jedi."
There's also the opening crawl to The Force Awakens, which goes even more obvious: "Skywalker, the last Jedi."
So yes, this is definitely referring to Luke - but it could, as many of these titles, have more than one meaning. The Return of the Jedi, for instance, referred both to Luke Skywalker becoming a Jedi knight, and also to Anakin Skywalker being reborn in the light side, becoming a Jedi again before dying. With that in mind...
Rey could also be The Last Jedi. After all, the Force awakened in her (though the dark side also awakened, and Luke was found - see what we mean about those multiple meanings?), and she's off to train with Luke. Rey being the Last, however, seems odd, since thus far she's been much more about beginnings than endings. She could also be the last one trained in the ways of the Jedi, then become something else. Our understanding of the Force as an audience has been changing as characters like Lyra Erso, Chirrut Îmwe, and Kanan Jarrus have changed in their understanding of it, after all.
Formerly Ben Solo, currently Kylo Ren, the title could also be referring to him - After all, he did train with Luke. Perhaps Luke will train Rey, but not as a Jedi, as something different, something new. Luke left and exiled himself to the first Jedi Temple at Ahch-To, abandoning teaching altogether; if Ben was the Last jedi, then maybe he's given up on the Jedi Ways as we know them.
A Group of Jedi
Jedi can be plural - and there could be more out there. We don't know anything about Luke's self-imposed exile. We know his students were slaughtered by Kylo and the Knights of Ren but could there have been survivors? Children are still being born in the galaxy, which means there are still new Force sensitives emerging, so it could be about a next generation group as well.
Whatever the case, whether it's just Luke or much more, Star Wars: The Last Jedi whould have fans debating for the next several months, until it comes out on December 15, 2017.