Rumors of a replacement for Rock ‘n’ Roller Coaster have existed for several years, but most of them seemed to be speculative.
“Blue Sky” possibilities include a Monster’s Inc/Monstropolis themed area that would include most of the Animation Courtyard. A Marvel overlay or another option.
November 16, 2018: The New York Times posted an article indicating a replacement is coming for Rock ‘n’ Roller Coaster. Disney has denied the claim.
October 29, 2018: On Episode 185 of the Unofficial Guide’s Disney Dish Podcast, Jim Hill suggested that Rock ‘n’ Roller Coaster could undergo a theme change soon.
June 17, 2017: On the recent episode of the Unofficial Guide’s Disney Dish Podcast, Jim Hill mentions that after Star Wars Land opens, Disney is looking at replacing Animation Courtyard with a Monster’s Inc themed area that may also include a re-theme of Rock ‘n’ Roller Coaster.
October 28, 2016: @CarouselOf on Twitter is reporting that Guardians of the Galaxy is coming as a replacement for Rock ‘n’ Roller Coaster.