This is more complicated than you're implying; they don't just pass the script around, potentially letting out leaks, for the sake of continuity in the wider areas of the franchise. They don't care enough about continuity for that. Not only will JJ be given the right to change whatever he wants on set, I doubt the script is even finished anyway. It's not like they can call over and say, "Hey, are you using Mara Jade?" because the most likely response is, "I have no idea who that is!" which doesn't definitively mean she's retconned out of existence, but it doesn't mean she's not; what if, say, they mention that Luke was never married, or give his wife a different name? This is just one scenario, but I'm trying to make the point that these people don't have the encyclopedic knowledge that we do, and you can't take that for granted. Anyway, the point is moot, because as a rule, T-canon producers just don't elevate specific characters out of C-canon status. Whenever it has happened, it's been incredibly vague (a'la Delta Squad and that one Hutt). The precedent has not been set, so why would anyone believe it was going to happen now? Hope is one thing, but expectation is unfounded.