Now we know that Star Wars Episode VIII will be called The Last Jedi. So who is the last Jedi? Let’s not belabor it. It’s Luke. The Last Jedi is Luke Skywalker.
I’ve laid out what the prophecy of “bringing balance to the Force” means in terms of Star Wars’ ring cycle. [In Star Wars: The Force Awakens, the Answers Hide In Plain Sight] It bears repeating that in Episodes I-III, we see Anakin Skywalker turned to the Sith — the dark polar end of the Force. In Episodes IV-VI, we see him brought back to the light polar end — the return of Anakin the Jedi. Structurally, it makes sense that the final ring in the saga will be the emergence of the prophesied balance between dark and light.
Luke Skywalker figured it out. He wouldn’t have saved his father in Episode VI had he not tapped the strength of the Dark Side to physically defeat Vader, but then brought himself back under control to spare Vader, once beaten. Luke was never indoctrinated into the Jedi’s pitiless stance against forsaking duty to rescue loved ones. Guided by his compassion instead of Jedi dogma, he was able to do what Obi-Wan and Yoda could not.
By Episode VII, Luke has suffered a disastrous failure trying to be a Jedi Master, and his students are dead by the hand of his Dark-seduced nephew. So he fled to an ancient and lost Jedi Temple, to learn something that neither Obi-Wan nor Yoda had taught him. It’s not a stretch to guess that, spurred by his experience with Darth Vader, he was in search of the true nature of the Force, one that neither Jedi nor Sith had mastered. He has learned about the Balance.
Now Rey has come to him, a Force-strong young woman in need of training. Luke won’t repeat the mistakes of the past. He will remain the last Jedi. The purple light that bathed Rey’s and Kylo Ren’s faces as their blue and red lightsabers clashed was no accident. When Luke trains Rey in the Balanced Force, she will become something new, requiring a new name. And after the Revenge of the Sith and the Return of the Jedi, I’m confident that the new name will figure into the title of Episode IX.
UPDATE 1
The non-English movie posters have revealed that “Jedi” in the title is being used as the plural. So it’s not just Luke. But no matter how many there are, the fact that they’re the last is what’s significant. The reasoning stands. After this set, Force practitioners will be something else.
Oddly, the French translation of Return of the Jedi was Le Retour Du Jedi — singular. Which rather minimizes the impact of Luke’s journey.
UPDATE 2
I take the last line from the teaser trailer for The Last Jedi as confirmation of all the above.