James Mangold's Star Wars movie will center on the very first Jedi, meaning the story can also show the Force's origin. Star Wars has explored the Force's origin before, both mystical and biological, but no story has depicted it in detail. Now that Dawn of the Jedi is taking the franchise farther back in time than any canon source so far, there is a perfect opportunity for the new Star Wars movie to show the Force's origin. This would tie in nicely with the beginning of the Jedi Order, explore the Force's nature on a deeper level, and weave together several story threads throughout the Star Wars timeline.
Even though Mangold and his team will bring their own ideas to Star Wars, showing the Force's origin would also honor George Lucas' original plans. In his version of the Star Wars sequel trilogy, Lucas would have explained the Whills and midi-chlorians by revealing more about the microbiotic world of the Force. These plans never came to fruition, but Lucas' concept of the Whills is similar to other aspects of the Force that have already been introduced in canon. Mangold's Star Wars movie can build off these ideas to finally show the Force's origin and how it led to the Dawn of the Jedi.