It might take another 20 or 30 years like SW77, but eventually we’ll know more.
Maybe. I don’t expect the level open-ness from Disney ever the way we eventually got with LFL & Rinzler.
Rinzler did actually write and edit an entire Making of TFA book, that was cancelled.
https://www.slashfilm.com/546017/j-w-rinzler-the-making-of-star-wars-the-force-awakens/
He started work even before Abraams was brought on board, and interviewed nearly everyone involved. He compared it to his ROTS book, so it wasn’t going to be as open as the 30-years of hindsight for the OT books, but it was still to be a very comprehensive 368-page epic.
I hope that one day it’ll come out, but with Rinzler’s passing, it seems unlikely.
Anyway here’s a brief bit of info about that whole ‘extra hour’ thing:
https://www.businessinsider.com/star-wars-force-awakens-unused-footage-2016-4?r=US&IR=T
Of course the guy who worked with all the puppets would want more of his work seen. Everyone who works in production design always does.
Editors Maryann Brandon and Mary Jo Markey have stated that the first pass was 2:30
[Mary Jo Markey said:]
It wasn’t too bad. I think it was about two and a half hours, right Maryann?
[Maryann Brandon said:]
Two and a half. And JJ really wanted it to be two hours.
Lot’s of great info in their Art of the Cut article here;
https://www.provideocoalition.com/art-of-the-cut-with-the-editors-of-star-wars-the-force-awakens/