I don't blame Oz. I liked this movie. But to me, it's a bit like doing another Marx Brothers movie. You can find people to portray the characters, but it's just not the same. The original creative force of the show is gone.
For reviving the Muppets, I dunno. The Muppets really ceased regular production long before Jim Henson's death. They became other projects. Fraggle Rock, Dark Crystal, Dinosaurs, etc. They're entertaining. But there's really nowhere for the characters to go. I'd settle for FINALLY getting seasons 4-5 on dvd.