There's still a chance that Disney could follow suit of what some companies do, and rather release Season 4 and 5 individually, just put out a complete series set instead, which would **** me off.
Shout! Factory is doing this with GREEN ACRES, and it's been twelve years since MGM released the previous seasons on DVD. Universal did the same with LEAVE IT TO BEAVER: first two seasons individually, then just went straight to a complete series set.
I'm not saying I look for this to happen though; next to Warner Bros., Disney is probably the worst studio when it comes to releasing things on DVD (and ironic that Disney has to have its own, registered and trademarked brand of DVD).