Here's the rumor tracker that I closed out with the TCM update. I'll be re-opening a new one with much of the same info:
September 18, 2015: Twitter user
@Schmoofy has reported that the temporary planters in front of The Chinese Theater have been removed.
September 11, 2015: The temporary stage has been complete removed and the view of the Chinese Theater is now unobstructed except for temporary planters.
August 20, 2015: WDWMagic.com user marni1971 has reported that the spires on the Chinese Theater should be added back this weekend.
June 1, 2015: @touringplans posted an image on Twitter of the new exterior signage/marquee for The Great Movie Ride. The marquee now features Turner Classic Movies logo, this was reportedly updated a few days ago.
May 30, 2015: @Attractions posted the updated finale film on Twitter.
May 26, 2015: @themetaphorgirl on Instagram posted a photo of the new interior marquee in The Great Movie Ride.
April 16, 2015: @laughing_place reported on Twitter that the pre-show and Finale scenes for The Great Movie Ride have been updated to digital projectors.
February 10, 2015: WDWMagic.com user danlb_2000 reported that Disney has filed a Notice of Commencement with the description, "Chinese Theater Turrets".
February 3, 2015: WDWMagic.com has posted photos of a small construction area next to The Great Movie Ride. It is possible this will be a photo opportunity for guests.
January 20, 2015: WDWMagic.com user tirian has reported that the speakers on The Great Movie Ride are being updated scene by scene. Reportedly, the musical, sci-fi and western sequences have been updated.
January 6, 2015: WDWMagic.com user danlb_2000 has reported that Disney has filed a Notice of Commencement for a graphics package at The Great Movie Ride.
December 12, 2014: In a series of tweets, @JimHillMedia revealed details on several components of the Hollywood Studios expansion. This included an update on The Great Movie Ride:
The Great Movie Ride overhaul that will follow the Turner Classic Movies changes will take place in 2020-2021 when the Star Wars and Pixar components are brought on line. (Tweet)
December 1, 2014: On Episode 68 of the Unofficial Guide's Disney Dish Podcast with Jim Hill, Jim clarifies that the Turner Classic Movies update will be for the pre-show, finale movie and potentially in ride audio. He did not expect substantial changes to the show scenes themselves. He also mentioned that this may not prevent Disney from making a substantial change to the attraction in time for the resort's 50th anniversary in 2021.
November 26, 2014: Turner Classic Movies launched a website about the Great Movie Ride sponsorship that also included a press release. The Orlando Sentinel identified this as a 5 year deal.
November 26. 2014: WDWMagic.com user wdw71fan has reported that the search lights will be returning to the Chinese Theater.
November 25, 2014: NewYorkTimes.com has reported that Disney is partnering with Turner Classic Movies to update the Great Movie Ride. The timeframe is expected to be in the first quarter of 2015. This appears to have changed the future of an attraction previously believed to be on the chopping block.
Changes are expected in the pre-show video as well as the finale video. Turner Classic Movies will also appear as sponsors on attraction signage. There were no details that indicated any changes would be taking place to the show scenes.
October 28, 2014: WDWMagic.com user WDW1974 has reported that as part of the Hollywood Studios overhaul, the only attractions guaranteed to remain in some capacity are Rock 'n' Roller Coaster, Toy Story Midway Mania, Star Tours and Tower of Terror.
October 26, 2014: At a TouringPlans sponsored event in New Jersey as well as on the TouringPlans Twitter feed, Jim Hill reported that the trackless ride system will not be added to Hollywood Studios until they replace Great Movie Ride.
October 24, 2014: WDWMagic.com user Disneyhead'71 has posted a rumor that The Great Movie Ride could be replaced by a Guardians of the Galaxy inspired concept. The story of the rumored attraction would be that guests are attending the premier of Guardians of the Galaxy when they're put into the action in an LPS (Location Positioning System) vehicle. Other examples of LPS rides include Pooh's Hunny Hunt at Tokyo Disneyland, Mystic Manor at Hong Kong Disneyland, and Ratatouille: The Adventure at Disney Studios Paris.
August 10, 2014: On Episode 62 of the Unofficial Guide's Disney Dish podcast with Jim Hill, he mentioned that The Great Movie Ride would close as part of the overhaul taking place at Hollywood Studios. The attraction has several corporate events scheduled though so closure is not expected until 2017-2018. The replacement of the attraction has not been determined.
May 14, 2013: OrlandoParkNews.com reported that The Great Movie Ride's refurbishment has been scaled back to three weeks with the only noticeable change being the finale film.