I've said it elsewhere, but i'm sure we will see dvd releases of the various specials - but not right away.
Disney outright owning the Muppets as a brand is a different situation than what the Muppets have had in the past - having a deal with a seperate company set up to distribute videos (which have an expiration date). Unless Disney sells the Muppets to someone else (which isn't going to happen), they have the Muppet brand for life. That means they don't have to rush. They can do things in good time and set up long-term marketing plans.
We know how Disney operates with its original material and other properties - the legendary "Disney vault" which every now and then something gets let out of..."but buy now - before it goes back into the Vault"!
Disney doesn't want to oversaturate the market all at once with Muppet dvds. Their big goal right now is the relaunch. That and the classic Muppet Show sets. The Big Guns. There's time for the more obscure stuff later (when the Muppets are at the peak of its relaunch plans, have gathered a new slew of fans and the demand for the earlier stuff is grown). They want to release stuff when the market value is up. When Muppet Mania is in full swing and people are clamoring for more, an older special will have more sales/value than a quieter release at a random time where it may warm the shelves.
It's frustrating and i think Disney could still do much more than what they've been doing as the dvds go (that was my big thing for Tough Pigs' Suggestion Box article) - but though patience may be required i do feel as far as Muppet dvds, the question is more "when" than "if".
In the meantime, TMS Season 4 is on the horizon (and though i can think of better bonus features, it should be noted each box set so far has had a Muppet special as a bonus feature...i'm hoping they go with The Muppets Go Hollywood since that was the timeframe) as well as a dvd release of a more recent Muppet special, Studio DC.
Slow, yes. Worth it, absolutely. And hey, perhaps the economy will be in better shape to where more people can afford a floodgate of stuff as opposed to now.