Given the whole "but what would Link do?" mess from 2016, I highly doubt Zelda will be playable. Heck, she seems to fall when the bridge(?) they're on in the trailer breaks so I think she's just going to be a damsel in distress. Again.
Of course I'd be thrilled to be wrong as I'm one of the people who always wanted a playable Zeldaand gender option for Link, but yeah - I don't see it happening.
I'm not opposited to having a female "Link" (would be kinda weird if that was her name), but having the SAME Link from BotW suddenly be female would be pretty strange. He's not a "blank canvas" or a representation of you as the player here, he's very much a specific character. You can't even name him something else like you normally can. So if there's any playable female character, it's gonna be Zelda.