Don't count on any new expansions for SWG anytime in the near future. It's taking them long enough to get publishes put in [around 6/7 months for chapter 7].
The devs have said they want to have the extra content come out in the chapter publishes rather then a seperate expansion.
On a personal note about your idea, you mention members of the Empire can help invade Ithor...what about the players in the Rebellion? Are they on permanent defense? Sounds like it would get old quick. Ah, I just noticed the date on the op - time for sleep.
That would make that a triple post