My understanding from all the between-the-lines I've been privy to since 2014 or so is that Disney bought Lucasfilm, part of the deal included Disney using the 7-8-9 treatments Lucas had come up with, pre-production ensued, going in that direction (a lot of this is in the art-of book, with younger Sam and Kira and all of that). Around the time Kathleen and the Story Group were reluctantly broaching the fact that the story was... not great... is when Kathleen approached JJ and told him they were going to be round-filing the treatments. That was what clinched it for him -- being able to be in on the story mapping from the blank page stage. I can't remember timeline for the other writers involved, and I don't feel like flexing my Google-fu right now to see, but that was parallel to all this going on on the decision-making level.
All the stuff people complain about -- Kira being the hotshot teenage pilot, scavenger, and mechanic, for instance -- is all there in the treatment. Just Like George's prior protagonists, Luke and Anakin. What can be gleaned of the story evolution from the art-of book alone hints at some of the awkwardness of the choice to ditch George's treatment and try again, using as many of the element from them as they could, so they could say they tired and this was just what it evolved into. As with the finished film, most of it I like. Not a fan of the Resistance or First Order organization names, not a fan of there only being TIE Fighters in evidence, not a fan of the misinterpretations of earlier films that krept into production design of this one... But overall I like it. It's probably number three on my list, after Star Wars and Empire. So they did a lot right, too.
Which is why all of this "controversy" over the making-of book irritates me. Why? Most of this is already public record, from interviews with the principals involved, from the art-of book, etc. And Rinzler has a track record of writing sympathetically toward people whom he could easily just tear apart. I've read all three of his big OT tomes cover to cover, and he never gets anywhere near "dirty laundry" kind of tell-all stuff. He doesn't hide anything germane to the evolution of each film, nothing that affected the outcome is glossed over... But neither does he name-call or cast aspersions. So my feeling is that if there's anything going on with this delay/cancel stuff, it's due to potential story leaks for 8 and/or 9. I need to check in again with my book store, but the last time I did it was still showing an October release. One guy talking to Rinzler said that his Amazon pre-order of the book had been cancelled and his money refunded, but mine through my book store's distributor hasn't been. SO I don't know what the hell's going on.
--Jonah