The problem I have with that is, well, if they're going to gradually turn the show into a Muppet Show remake, it better the heck be really darn gradual.I think it is a very good idea to upgrade "Up Late With Miss Piggy" to contain a more substantial "show-within-a-show" format like "The Muppet Show" and "Muppets Tonight"
While I do think the format can be tweaked to have a short skit or song here and there, I'd rather they go the 30 Rock route and show some of the skits so they don't take up the entire show. At least, at this point in the series. If they can keep the mix of behind the scenes and outside of the show plots, we may just have something. What I'd find ideal is for them to shoot sketches and put them up online as a supplementary experience. But that's clearly too much time and money involved.
I do feel the show could greatly benefit from showing more of the show than a fleeting interview, I just don't want to see attempts at trying to emulate old bits.