Regardless of your personal opinion, the Last Jedi was very divisive and it left the series on a shaky note. At this point there are very few Resistance members left and it is unclear where the story can and should go from this point. In addition, it is arguable that the audience relationship with many of the remaining characters is tepid at best.

JJ Abrams has been brought in to direct Episode IX, returning from directing the Force Awakens. Among others Dominic Monaghan, Matt Smith, and Keri Russell have been added and Billy Dee Williams is returning as Lando Calrissian. That is a lot of new and prominent faces to introduce to this trilogy, have them make any meaningful impact, and then wrap up the trilogy and series as a whole. So, to the point of my theory, what if Episode IX isn't the end to the series? What if the "sequel trilogy" isn't a trilogy at all, but a quadrilogy?

JJ Abrams is known to have a lot of secrecy surrounding his projects and Star Wars is known for its twists. What if the twist of Episode IX is a cliffhanger when the audience expects it to end the story? What if JJ Abrams' reason for returning is to shock audiences with Episode X?

An extra movie would give the filmmakers time to introduce the new characters and flesh out the current ones without having to rush through the story. Episode X would then be completely separated from the Original Trilogy and then resolve the new characters' stories without the need for appearances from Han, Luke, Leia, etc.

You may argue that Laura Dean, Kelly Marie Tran and Benicio Del Toro joined the Last Jedi and were able to be introduced without slowing down the plot. Without bringing up the Rose Tico controversy, these characters (with the exception of Holdo) still exist and will have to be addressed in Episode IX. Adding more characters on top of these just adds to the screen time that will need to be devoted to making these characters have any sort of impact on the story.

There is no hard and fast rule that Star Wars stories need to be trilogies, and with the release of Last Jedi, Disney certainly has a way of "subverting expectations." Obviously there's no evidence that an Episode X is in production, and I don't believe any of the Sequel Trilogy stars are signed on to a fourth movie (at least publicly). But Disney has confirmed its intention to continue to release Star Wars movies and due to the inherent secrecy that comes with the involvement of JJ Abrams I believe it is at least a possibility. What are your thoughts?