I just wonder why the Zora grew wings. It's not like being a fish in Water World would be useful or something like that.
That was just one example of the many sacrifices that had to be made for the sake of the plot. With Hyrule being submerged and all, we wouldn't want to have any Zora snooping around where they don't belong, would we? Keep in mind that I mean this in a figurative sense (as, literally speaking, the Zora
do "belong in an aquatic environment").
While I agree that Nintendo could probably have gone many a different route, such as justifying the disappearance of the Zora via extinction, I accept what they came up with in regards to the Rito.... somewhat.
As to the general topic... I don't expect to see the return of the Rito in future installments, as they no longer serve a purpose. TWW and its sequels have pretty much wrapped up that whole tropical, seafaring saga as well any chance of seeing the Rito again.
Regarding the Korok... I found the evolution of the Kokiri to be the greatest of its kind for the series; an excellent exhibition of change over the course of not only the in-game continuity but the series itself. Unfortunate to see what became of the Kokiri, though... I really miss those guys... :[