Had George Lucas' Star Wars sequel trilogy been made, a new canon would've been declared, and, ultimately, Disney did the same. Lucas spent time developing Episodes VII - IX over the course of several decades before seriously exploring the storytelling possibilities in the early 2010s, just a few years before selling Lucasfilm to The Walt Disney Company in October 2012. As part of the sale, Lucas included story treatments for each of the films in the sequel trilogy, with the understanding that he would serve as an advisor for the films while Disney funded and produced the concepts.
Lucas' treatments were infamously discarded by Disney, a situation CEO Bob Iger has come to regret, and director J.J. Abrams went on to co-write what became Star Wars: The Force Awakens with Lawrence Kasdan. The decision prompted Lucas to remove himself from the franchise entirely, though he remains available for discussions with creators and makes infrequent set visits. Disney and Lucas have struggled to see eye-to-eye since the sale, but both parties agreed that changes were necessary with pre-existing expanded media in order for the sequel films to tell a new story.
George Lucas' Sequel Plans Ignored The Star Wars Expanded Universe
From the outset, Lucas always planned to ignore the Expanded Universe and tell his own stories for the sequel trilogy. Had Lucas retained control of his company, a new canon was certainly on the way much like how things have transpired in recent years. The precedent for such a move has been out in the open since at least the Star Wars: The Clone Wars animated series was released, which overwrote a number of EU stories regarding the clones, Mandalore, and various Jedi. Lucas always maintained that the EU was available for all to enjoy, but it wasn't a part of his story.
There are only fragments of what Lucas planned for his sequel trilogy known to the public, but many of the details were in direct contradiction with the EU. Han Solo and Princess Leia only had one son, who also turned to the dark side, and would kill his father like Kylo Ren. Other plans included a hermit Luke in exile who would be found by the young heroine and brought into action halfway through Episode VII, a resurgent Darth Maul ruling over the underworld, and Chancellor Leia helping establish the New Republic for good. The ideas came at various points in development, but all went in unique new directions.
Disney Made The Same Decision As George Lucas
There was widespread outrage when Disney wiped the EU from the official Star Wars continuity in 2014, but it was a rare decision in lockstep with Lucas. In order to ensure creators the opportunity to have a blank slate, a new canon was created that, at the time, only included Lucas' six films and The Clone Wars. Every film, show, game, novel, and game released thereafter has joined the canon, unless otherwise stated, and the previous EU projects fall under the Legends banner. To date, hundreds of new stories have been added to the official continuity.
While the two parties agreed on the need for creative freedom, Lucas' biggest gripe with Disney's sequel trilogy is ironically the lack of new ideas. The Maker's feelings on The Force Awakens' derivative plot from A New Hope have been well documented, while he's since remained silent on the follow-ups. By all indications, Lucas is a big fan of Rogue One: A Star Wars Story, Star Wars Rebels, and The Mandalorian, none of which could've fit in the old EU's timeline. Branding the EU unofficial wasn't popular at the time, but it was an inevitable decision that has allowed for many new exciting Star Wars stories to be told.