I sincerely believe that Carousel of Progress is not only significant to the Disney company, but culturally signifcant as well. The attraction is the most performed stage show in the history of the planet and it celebrates the American family through the years. Beyond that, it is located in the number one tourist destination for families in the world. While it's popularity is very low, as an attraction it is not lowly rated. Moreover, it has been neglected for 22 years.
The relevance of the story and the emphasis on family and progress really make this an obvious choice for Epcot. I love the idea of this being an extension of the Horizons concept and I think every fanboy would be overwhelmed if Carousel of Progress moved to Future World East as part of a new pavilion (perhaps on the Wonders of Life footprint). I would suggest an old but new concept for a Horizons style attraction (for kicks, let's call it Century 3). The options for the ride system have increased significantly since Horizons debuted, but a suspended system could work with vehicles that have an even greater range of motion. This could be mini Soarin' style suspended seats to a regular or potentially even suspended Kuka arm.
At this point I'm well beyond the stage where this post belongs in the Imagineering forum, but if Disney truly wants to revitalize Epcot the bandaid solutions of Frozen aren't the only answer. To steal a line from the worst script in the history of Spaceship Earth, "The answers lie in our past." This doesn't mean bring back the 1983 versions of Epcot attractions, but it does mean they can use the spirit of those attractions and tell those stories in new ways.