As a huge Zelda fan I would hate to see a 'World of Hyrule' MMO.
Yes it has the races and a very big world to explore... but how would they implement objectives? Just a lot of Dungeons and Temples become 10 man raids? Does Link and Zelda decide to say 'fuck it, you guys go kill Ganon' I think that would be very stupid to have a bunch of no-names kill Ganon, unless they decide to pull a Tirion-Lich King bullshit. How would they make classes? Warrior, Sheikah, Sage, Marksman?
It's a bad idea because Zelda games are about being Link, the Hero. Not a rag-tag crew of Gorons, Zoras, and Gerudo...maybe a Skullkid or Deku scrub.
It would probably be something similar to Final Fantasy MMOs. And just look at how shitty the last one turned out. And FFXI is so damn grindy and slow. Japanese game devs should ONLY EVER stick to console gaming.