Going by unconfirmed reports from earlier this week, it looks like the next standalone Star Wars movie will focus on Obi-Wan Kenobi and what he was up to between A New Hope and Revenge of the Sith.
Although he pops up in the animated Star Wars: Rebels series, there's still a blank space in his storyline and that's where the film will focus. Further reports suggest that Mr. Robot showrunner Sam Esmail has had meetings with Kathleen Kennedy and Lucasfilm with a view to penning the screenplay, and given the huge success of Rogue One, it's clear that audiences are hungry for more Star Wars films - even if they're not in the same chronology as the series.
For his part, Ewan McGregor has said that he's more than open to reprising the role and his performance as Obi-Wan Kenobi was one of the highlights of the prequel series. Blending Alec Guinness' effortless charm with his own performance, McGregor really made the role his own - so the question isn't so much as to how he'll play the role so much as what the story will be.
Going by the events of Revenge Of The Sith, Obi-Wan Kenobi agreed to stay put on Tatooine to ensure that no harm came to Luke Skywalker and to be ready for him, should he come knocking. As mentioned, the animated series Star Wars: Rebels shows Obi-Wan Kenobi on Tatooine, so we know he's on the planet. But why is he still there? Why is he not out trying to save the galaxy from the Galactic Empire?
Essentially, there has to be a reason for him to leave Tatooine and it has to have something to do with why he was there in the first place - in other words, it has to have something to do with Luke Skywalker and Leia Organa. If you remember Revenge of the Sith, it was agreed that the children would be kept separate and their identities changed to make sure that nobody knew they were related and that Anakin Skywalker / Darth Vader would have no way of knowing.
So, essentially, the film is about Obi-Wan Kenobi keeping the children's identities a secret, and keeping his own identity a secret as well. After all, the Empire has wiped out the Jedi Order and Obi-Wan Kenobi is presumed dead - so he can't very well start waving his lightsaber because that'd attract attention. Instead, the film could have the tone of a spy thriller - almost like the Ipcress File or The Kremlin Letter - with Obi-Wan Kenobi using his wits rather than the Force.
From what we know from The Empire Strikes Back and Return of the Jedi, Darth Vader was aware that he had a son - but not a daughter. So evidently, he had bounty hunters or intelligence agents out there, scouring the galaxy for information. That's where Obi-Wan Kenobi finds out that Darth Vader are looking for Luke Skywalker. The film could see him criss-crossing the galaxy in an attempt to cover the tracks leading back to Luke Skywalker and Leia Organa, but what the film's emotional core is about Obi-Wan Kenobi trying to acknowledge his mistake.
After all, he took Anakin on as his apprentice and he has to feel like he's to blame for what ultimately happened to him. That's a particularly potent bit of drama; having to come face-to-face with his own failures as a mentor to him and ensuring that he can't poison his own children with his evil.
Lucasfilm executives, if you're reading this and like what you see, we'll take premiere tickets in payment and five points on the back-end.