Jamie,
I do fully acknowledge (and have done countless times in the past) that Fox has a slightly better track record than other networks of keeping ailing shows on air (Futurama for one) but this doesn't mean they are a charity and I think puppet shows, be they Muppets, ALF, Greg or any other are always going to get a rougher deal, basically because they are something a little different and the industry as of right now does not like to take risks.
I did not suggest the Muppets would get cancelled - i said they would probably get exactly the same treatment as Greg, meaning they would be given possibly at most two or three months chance at getting some decent ratings. I think this is being much more realistic than pessemistic and if you understand about how much the rights for an established brand like the 'Muppets' would cost compared to 'Greg' then you'd get just how much more of a financial risk them continuing to produce a Muppet show would be if things started to go wrong. Thats not saying it will go wrong though !
Speaking from personal experience - the Media industry has changed a lot since 9/11 and already in a slump, things have got dire. Especially in the U.S they are producing only what they can almost guarantee will be successes and doing a lot of cheap nostalgia stuff - basically sticking to that is cheap or formats they know best.
'Greg' getting cancelled could well be a bad omen for the Muppets, or, even though the new show is supposed to be innovative and edgy, the Americans might well embrace them as part of the nostalgia boom - IMHO i don't think it's a great time for them to be doing a new Muppet show, but hey - at least they actually got a deal !