GURPS World War II allows players to play characters from any belligerent countries, including nazi Germany, fascist Italy, red fascist USSR, military fascist Japan. If somebody was outraged by that it didn't make any noise. Is it because GURPS is unknown outside the world of p&p RPG ? Or is it because the 80's is well past and nobody gives a **** about RPG's content now ?
Personally I doubt LucasFilm will ever allow an Empire SourceBook because Star Wars is about fighting against the Empire, not fighting for the Empire. In all the official canon published so far, is there any that show a story about characters on the Empire side ? I never saw one but I don't know everything about SW canon, so I might be wrong. If I'm right we'll never see an Empire Sourcebook published by FFG. If I'm wrong there's a very tiny hope to see one someday in the future.
The same reasoning could be applied for the possibility for a KotOR era sourcebook to be published. Would it be genuine without Sith careers, imperial troopers careers, imperial Intelligence careers, and an extensive description of the Sith Empire ?