There's also that bit about george asking the question 'what happens to anakin's/vaders grandkids' - plural.
Not sure who writes the Art of books, but i'd wager LFL has say so over whether or not they go to press, if not control the whole thing. Gotta take those things with a grain or two of salt.
The OT wasn't fully planned out ahead of time. George, originally had 12 flicks planned out in his head. Started at 4, but whittle it to stand alone flick as there was no guarantee of any more. After it was a success he moved forward, but wound up condensing at least 6-9 in ROTJ as he didn't want to continue another 10 years. So, while it wasn't completely planned out - he did know where it was going. The ST? They do their damnedest to make sure everyone thinks they have no clue. Unless they're trying to perpetuate a massive fake out somehow - there's no reason to end all your story points in part 2 of a trilogy. There's absolutely no indication anywhere that JJ and RJ were not given full carte blanche to do whatever they wanted.
You're not getting anyone to believe that without having george's actual treatments. Just not happening. IF they were, he half assed his way through them based on what we've seen to this point.
Just in the first two tweets of that link, two descendants become one, the one doesn't get corrupted, he just 'is' when we meet him, snoke was created off a different idea, etc. Doesn't sound like it follows the treatment too much. Also seems the article's defense is that 'he could have changed his mind later'. While that could betrue, it would seem to be completely buying the corporate tag line. Which i seriously doubt. Also, if that's true, why wouldn't they acknowledge it from the get-go and not only AFTER there was lots of blow back? George wouldn't have trashed luke. That's on RJ i'm sure.
I'm sure elements were kept, but i'm guessing the overall story line wasn't. A Jedi Killer named Talon? Implies luke did restart the Jedi. Otherwise, how can you be a jedi-killer? An inference to that was that Skyler (i.e. Ben) knew Talon and that in the end of 7 or 8, Luke takes down Talon which pushes Skyler off to the dark side Seems very different that what we got. Different to the point of tossing the orignal outlines. Taking a queue here and there does not amount to largely following the treatments.
Again, the word we have is the corporate office who, face it, is a level of damage control. They want us to believe they're telling the truth, give us the treatments. Simple as that.