here's what might happen.
>won't actually be playable in the sense you'd expect
>she'll be actively involved with the story like Tetra or will be the Midna/Navi/Fi of the game
>you'll get something like the command melody in wind waker and have moments where you take control of zelda to do certain things
>extremely limited moveset, all she'll probably be able to do is run and jump and crawl, most likely will only be used for pressing another button in the same room.