I wouldn't worry folks...
I think the concern surrounding the new movie can be attributed to a couple of things:
1) Mirrormask - It was pretty much made known by the company that they put this movie into production as a result of the fantastic DVD sales the original Dark Crystal and Laybrinth were yielding. I think that confused people into believing that this project was going to be of the same scale, which of course it wasn't. I believe they wanted to add to their fantasy portfolio, and as much as I loved the movie, it was never meant to be a blockbuster, more likely a DVD lead product to package and sell their home entertainment line. With a 4 million dollar budget (I believe), I seriously doubt the new Dark Crystal movie will be anything like this project. Mirrormask was amazing for what it was.
2) Cheap Sequels - Im sure a lot of posters here would rank the original Neverending Story amongst their favourite movies, and in turn were heart broken by the 2 sequals that followed. Those 2 flicks lacked the soul of the first, and were probably more hollywood trying to quickly cash in on the success of the original. I really think that development was clearly rushed, as if just putting out anything with the Neverending Story brand would yield profits. Needless to say, it didnt work. Fans recognize this kind of thing in the business and are probably terrified the new Dark Crystal film will follow the same pattern. The company obviously knows the potential continuing this franchise, however there is no way the Henson kids are going to take their fathers crowning achievement and ruin it.
Original actors, original conceptual designer, original writer and and amazing new director ... Ive heard its been pushed back to fall 2008 now (so much for Cannes), but thats OK by me, they can take as much time as they need, it tells me they aint rushing anything. Don't worry, they are going to do this thing right, Id bet my bottom dollar on it, it's going to be incredible...