Rumor StatusBlue Sky
Disney is rumored to be exploring the concept of an interchangeable attraction that would allow for quicker changeover and regular refreshes. Initial rumors had this concept as a Disney's Hollywood Exclusive, but the idea may be used at other parks as well.
Conflicting reports have the scope / scale of the attractions ranging from a larger trackless attraction that would be heavily reliant on screen based technology to smaller scale attractions.
With limited details on the concept, we are considering this Blue Sky.
May 5, 2019: WDWMagic.com user marni1971 is indicating that while the concept of an interchangeable attraction is under consideration, it may not be as substantial as previously reported. It is also expected to not be unique to Disney's Hollywood Studios and the timeline is unclear.
April 30, 2019: WDWNT.com is reporting that Disney is exploring the concept of a "Black Box" ride building in DIsney's Hollywood Studios. The attraction would be trackless and heavily reliant on screen based technology allowing for quick changeovers to new attractions and constant refreshing.