As President of the U of Minnesota's Mel Brooks club I have to voice my opinion on this.
I agree - Mel's brand of humor, specifically Blazing Saddles and The Producers is great, however you would not be able to make a movie like that today. People would think it's insensitive and get all offended. I also agree that the humor Mel does isn't exactly something that would work coming out of Fozzie's mouth, you know? Just a little too risque.
While I think it would be great to see them come together (again), Mel is a talented comic director, he could turn Schindler's List into a funny funny movie, but he gets kind of wild and he'd need to be a little censored, which would take the wind out of his sails... so I don't think we'll see it any time soon, sadly.
Jeremy