What would be happening if/when this closes would be a complete gut job, no quick refurb.
From what I know about the rumor, Disney originally wanted GMR to close almost 3 months ago at the beginning of January. They originally wanted the new ride to open for 2019 and may still be aiming for that, which could be why they want to close it in the fall if that's what they decide to do. Of course, they could always push it back until after TSL, but this is is something that seems less a matter of if and more a matter of when. Disney is done with the GMR.