Obi Wan is pretty much the last character left that truly should receive a spinoff. Afterwards, Disney’s probably going to go crazy with the Old Republic and Legacy eras or reboot the prequels. Pitch the movie or first read my pitch for inspiration:

CRAZY OLD BEN: A STAR WARS STORY

Set between Episode IV and Episode III
Completes Obi Wan’s transformation into a wise Jedi master and Anakin’s transformation into the badass Darth Vader
features a grudge match between Darth Vader, Maul, and Obi Wan Kenobi
Darth Vader searches for Obi Wan desperately in order to exact vengeance
Obi Wan learns the true way of the Force alongside Yoda (midichlorians and all the stupid prequel stuff are debunked)