For
Mt. Olympus, someone earlier (sorry forget who) proposed folding it into the Atlantis land - seeing as they're both Greek. So if we're still keen on stuff like incorporating the Hercules cartoon or the Muppets Greek stage show (the latter is something I'm a big fan of), we can still do those.
Wakanda works as a slightly more sci-fi land which still keeps the park's theme. (
@spacemt354 tries quoting Ulysses Klau of all people to discredit Wakanda, which is silly talk.) Plus, Wakanda satisfies our desire for an African lost world while doing something different.