I WOULD play a Zelda MMO, but I don't think I'd enjoy it. Zelda isn't known for multiplayer gameplay, Four Swords, FSA, and the multiplayer games of Phantom Hourglass/Spirit Tracks were hardly played let alone even looked at. Making an MMO would only hurt Nintendo's sales and would be kinda awkward to have as Zelda is a linear storybased series rather than a branching series that can lead to any result. Of course, you could have the main story be single player and then have a noncanon MMO addition to it, but then again I can't imagine a million Links running around doing different objectives, it just wouldn't be the same. We've had 4 Links and that was understandable, many more would be overkill.
Take the upcoming Kirby Mass Attack game for example. That game has multiple Kirbys running about doing various tasks. Yes, in Nightmare in Dreamland, Super Star Ultra (and Super Star I think), Amazing Mirror, and multiple other Kirby games 4 Kirbys made a playable appearance. But it's never been more than 4, so going from 4 to a vastly larger number like 100 would be rather weird and some important features would be lost in that transition.