This was years before Disney and Lucasfilm started working on these standalone Star Wars movies, so John Knoll just sat with the idea for what would become Rogue One: A Star Wars Story.
As it turns out, Rogue One: A Star Wars Story was actually conceived as a TV show at one point.
Lucasfilm will probably venture into live-action TV shows in the Star Wars universe at some point, but it is for the best that Rogue One wound up getting made as a movie.
Rogue One: A Star Wars Story is now available on DVD/Blu-ray and VOD.