Cantus is right to a point. The magic that Jim had is gone, but I still think the magic can live on. It will just have to be a different kind of magic, and it needs to be found. The question is where can we find this other source of magic?
Another thing to look at is Sesame Street, they've been doing quite well on their own without Jim and true they had to fill a gap for sometime. But I think now SS is starting to reflect the magic there once was.
The Muppets just need to do the same thing, and stuff like this takes time.