Please note, this is still very much a rumor.
Disney long ago claimed its intention to release multiple Star War films, with episodes in the new, upcoming trilogy supplemented by spinoffs, ostensibly released in the years between. We now have a new rumor that one of those spin offs will be a Boba Fett prequel written by The Empire Strikes Back and Raiders of the Lost Ark scribe Lawrence Kasdan – at least according to Metalocalypse director Jon Schnepp, who claimed on the AMC Movie Talk Podcast (which was then recounted by Aintitcool) that he knew this “for a fact.”
“One of [the standalone Star Wars prequels] is Boba Fett,” said Schnepp, “It is. I know. I know for a fact. I will never reveal my source, but it is the one written by Lawrence Kasdan.”
The source is admittedly a little unusual, but there is a connection. Schnepp directed 34 episodes of the Adult Swim cartoon Metalocalypse, which is aired by the same network that aired the Lucasfilm Star Wars Clone Wars series. Yeah, definitely still thin.
The whole thing should be taken with a grain of salt, but it does confirm previous rumors regarding both a Boba Fett prequel spinoff, as well as Kasdan’s involvement with the brand beyond his current work with J.J. Abrams on the script of Episode VII.
As noted above, at the moment this is is still very much a rumor, and even if it is true it may be years before we see the film. With Kasdan deep at work on the first film in the new trilogy, it’s unlikely that he would have time to write another Star Wars film until this one is well into development. If Disney does go with the “one Star Wards movie per year” policy, as is widely assumed, and Kasdan is indeed working on a Boba Fett film, it would likely be released between Episodes VIII and IX, potentially putting it in 2018 or later.