I always thought something like this would be interesting to try in a game. Not getting rind of Link as the playable character altogether but have areas where you can switch between the two. The ideas a bit like how switching between Medli and Link in WW, except she has a full set of her own moves, not just run and fly.
Basically I think she should go on the adventure with you, kind of like
ST, but she alive and well this time. Most of the time you can switch between Link and Zelda. Each of them have different abilities. You'll have to move between the two in order to overcome different obstacles which normally can't be soved on your own. If you think about it, it would really give them a ton of different ideas in order to create puzzles in the world as well as making Zelda earn her place on the title. Also, if Nntendo really wanted to go the extra mile with it, they could try adding like a coop option with something like this.
So I guess I'm mixing in ideas from WW,
ST, and
FS/
FSA here, but I think something like this could really work out well. Plus if they wanted to do another romance thing between Link and Zelda, they could go crazy with it on this one.