People who claim the Muppets have lost their edge or havent been good/entertaining in the modern period have probably not seen the Muppets.com or youtube videos. I can't see how even a casual/non fan wouldnt be thrilled by those.
The Muppets were created to be around forever. It wasn't one guy doing everything, like Charles Schultz. The Muppets began in 1955, and will hopefully be around in 2055. It encompasses endless worlds...from The Muppet Show, Sesame Street, Fraggle Rock and Bear in the Big Blue House to The Hoobs, Mopatop, Dinosaurs, Animal Jam, etc.
I don't see the Muppets as some nostalgic trip from the 70's, always disliked that angle. Heck my favorite Muppet period is the late 80's(86-90)
I know there's Disneyana fans that do not like anything post Walt Disney's passing, and that's fine. And I admit it's been quite a rough patch...at times, a train wreck hard to watch(Oz, a lot of MFS, the EMTV thing, the 5 years Disney didnt do anything for the Muppets, etc) I've been on this site since the late 90's hoping for this day to come that Disney is giving us...but I also am realistic that the movie and reception might fall way short/be disappointing. But I'm excited, it's quite extrordinary actually