Well, what we would probably have seen is a blending of something akin to Great Movie Ride covering wider variety of aspects in Arts and Entertainment, with a section devoted to the future towards the end of the experience.
Personally, I think I would have preferred it that way. What would have really been cool is if the attraction/pavilion served as a gateway to a sub-park of EPCOT Center that would essentially be what became the Disney-MGM Studios. The concept was that the pavilion would be between Journey Into Imagination and The Land. Imagine that they configured what is now the EPCOT Resort Area so that 'EPCOT Studios' would essentially be where Yacht & Beach Club and the Walt Disney World Swan & Dolphin are now. Crescent Lake would be of a different size and shape, and have the sub-park along one side, and the Resorts on the other. From EPCOT Center, you would do the Arts and Entertainment attraction, and if you had the proper admission you could disembark on the other side into EPCOT Studios. Or, if you don't want to do the attraction, you could traverse large catwalks over the ride (giving you a bird's eye behind-the-scenes view on the way) to enter the sub-park. As EPCOT Studios expanded, an additional entrance and could be added along World Drive.