Found the article from Jim Hill on what could have been with the Muppets and Disney...
http://www.laughingplace.com/News-ID115390.asp
Here are some of the better quotes
"These days, I go into that park, wander back to where "Jim Henson's MuppetVision 3D" is and then ... Well, I just get wistful. Thinking about the other great Muppet related stuff that was supposed to be built back in this corner of the park. The Great Gonzo's Pizza Pandemonium Parlor. The Muppet Movie Ride ... Plus those wonderful Muppet themed street shows and parades that Jim Henson & the Imagineers had whipped up that were all ready to go ... "
"Okay. Let's not talk about that stuff yet. We have plenty of time to get to the sad part of the story. For now, let's just concentrate on what I like to call the Muppet Nearly-Wases: The parade & street show that were supposed to have preceded MuppetVision 3D into Disney/MGM.
There are probably a few of you out there who managed to catch the Muppets in their earliest performances at Disney / MGM. This was back in the winter of 1989 / spring of 1990 -- when the characters' appearances in the park were limited to Kermit & Miss Piggy's extended cameo toward the end of "Hollywood's Pretty Women" (This is the stage show that used to be presented at the old Theater of the Stars. Back when this Hollywood Bowl knock-off was located just off of Hollywood Boulevard, rather being hidden behind a hillside on Sunset Boulevard).
Anyway ... The gist of the Muppets "Hollywood's Pretty Women" performance is that Kermit came out & did a quick number with the chorus girls. Then the backstage gates next to the theater opened and Miss Piggy -- in all her splendor -- rolled out in front of the audience in the Theater of the Stars, riding in an enormous pink chauffeured Cadillac. Climbing out of her car, Piggy got up on stage and did a number (A great tune whose title escapes me at the moment) which stopped the show cold. Then Kermit, Piggy & pink Cadillac exited and the chorus went into the usual finale for the show. "
Plus much more stuff it''s quite an intresting read of what could have been. you also need to read part 4 of the article.