The reason Walt Disney Studios has pushed Star Wars: Episode VIII back seven months could be chalked up to last-minute re-writes, according to The Hollywood Reporter's Borys Kit.
"Obviously the December date worked out very (very) well for them but I've also heard they are rewriting the script," Kit tweeted. "I've heard from several sources the rewrites are positive, based on audience reaction to the new characters. People loved them. So strongly. And Lucasfilm was surprised at how well they were received, according to several sources."
Now set for release December 15, 2017, Rian Johnson's untitled Star Wars: Episode VIII will go up against Stephen Spielberg's Ready Player One and, perhaps even more interestedly, will come out just ten days before James Cameron's sequel to Avatar.