I was thinking they should convert their spaces into more legitimate ride spaces instead, which I have posted on more than one occasion in the Imagineering section. The Goofy space would become home to a fun little car ride through his house, something of a cross between Mr. Toad and Autopia, where you drive little cars through his house accidentally.
The Donald space would be rebuilt and take over the Gadget space as well, converting it all into a space for a new kiddie coaster, themed to Donald, where he has apparently started his own sky school, like Goofy has over at DCA, where, of course, things go wrong. I felt that a coaster would fit Donald's quick temper just as well as Goofy's ineptitude.
An alternative to the Donald idea would be to give the Gadget concept a retheme to something like, say, Ludwig Von Drake, who is testing some new invention and he invites you to test it out for him as his guinea pig. The coaster aspect shows that he still needs to work out some bugs. Of course, it would also mean that Donald's Boat would remain, which would be too bad, given the need for a serious spruce-up.