Hey! I've just heard that there's a new Star Wars movie being finished! It'll be the third episode of the prequel trilogy!
Now, listen to me, I have a conspiracy theory.
You know that George Lucas (thereafter referred to as Jojo) likes secrecy, NDA, and all these things.
Imagine that the WotC Star Wars RPG authors were "in the know" about the new plot, characters, vehicles, races, and other stuff that'll be introduced. They would have been constrained by NDAs not to reveal all that until the movie is released. Seems possible.
Now imagine that they had the choice between working on new books in secrecy and say nothing about it, or write material that doesn't allude to Ep. 3 and will be obsolete shortly after publication? What would you chose?
I predict an avalanche of products after Ep. 3 is released. A definitive sourcebook on the prequel trilogy, maybe a new revised edition of the core RPG (which is full of missing plot elements, like "nobody knows what happened to Anakin when he became Vader", and after Ep. 3's release, everybody will know).
And then, there will be Ep. 7--9 ! With all new monsters, starships, plot hooks, force powers, prestige classes, and character! Expect lots of other books!
Seriously, Hasbro (and thus Wizards) detains the SW franchise until 2018. They can afford a few waiting period for new (film) material to be released so that they can integrate it in new (game) material.