That was me. I liked the fresh water caverns in
OoT, and I would love a city like that, I am not too keen on an Atlantis type city. If it was in Hyrule, there would be nowere to put a gigantic city, since Hyrule is landlocked.
Anyway, the zora evolving into Rito would be better, because overwise they would be extinct in Hyrule (like I think the Gerudo are). It means they might de-evolve back. Medli gives you her grappling hook, saying that is what Rito used befoe they evolved wings. That may or may not be a reference. But I can't really imagine the Zoras evolving into Rito myself, they are just completely different races.