It seems like every day we learn more and more about a movie that we're not even 100% sure actually exists, but now we have rumors of an actual plot attached to the equally rumored Obi-Wan Kenobi movie. While Lucasfilm has yet to let the world into their plans post-Episode IX, rumors have continued to swirl that not only do they have a plan, they've already begun pre-production on a Star Wars Story spinoff film about the life of Obi-Wan Kenobi that would be set between the original and prequel trilogies. While none of this has been confirmed, it's now being reported that a production bulletin that includes a plot synopsis has leaked, which claims the new film will see Obi-Wan Kenobi be forced to come out of hiding when tensions between local farmers and a tribe of Tusken Raiders, led by a ruthless war chief, rise to a breaking point.
While all of this, from the plot synopsis revealed by TMZ to the existence of the movie itself, needs to be treated as rumor until such time as it's been confirmed by Lucasfilm, a lot of rumors about this particular project seem to be coming out of the word work, and there aren't a lot of rumors about any other Star Wars movie being planned for 2020. Unless we think Star Wars is actually going to take a year off, and I certainly don't believe that, the studio has to be in the early stages of working on something and this makes as much sense as anything.
While many of the rumors, like a planned start to filming, are generally vague, others, like this plot, and even the film's potential director, Stephen Daldry, are quite specific. That certainly gives them the feel of legitimacy. The only fact that we really have is that Ewan McGregor is more than willing to reprise his role as Obi-Wan Kenobi, and he's currently the perfect age to play the role mid-trilogy.
The plot suggested here certainly works as far as it goes. It would allow for the character of Obi-Wan Kenobi to get involved in a situation that would have plenty of action and tension, without it being on the level of the whole Rebel vs. Imperial fight. It wouldn't make sense from the perspective of the larger Star Wars universe for Obi-Wan to draw too much attention to himself since he's supposed to be hiding, but a local skirmish on the planet furthest from the bright center of the universe would be just about right.
One of the more important pieces of information that has not yet been rumored, is who wrote this synopsis. If there's a general plot outline, somebody had to create it, and that person is likely working on a script right now, assuming it hasn't already been completed. It's a pretty key detail that has surprisingly remained uncovered, assuming any of this actually true.