I was always hoping for a Clone Wars Era book, and now that Dawn of Rebellion is a thing, I'm sure that's coming down the pike sooner or later. I'm not too sure about the ST. I love the movies, but I'm not sure about it as a roleplaying setting, but then again, I've never really given it any thought. It could work, but I'm personally not in any kind of rush to see a ST sourcebook.
It's only quasi-related, but what I'm hoping for is an Imperial Sourcebook. Not a book with rules for playing Imperial characters, that would be pointless, since there's nothing stopping you from doing that with the existing rules. What I mean is a book that goes deep into exploring the Empire. What is the political hierarchy like? What is daily life like for the average citizen on an Imperial controlled world? What is the Imperial Military structure like? I realize that a lot of people might already know this stuff from the EU media, but aside from some video games and a few novels and comic book series, I didn't read too much of it.