What diversity nuts need to understand is that you can't shoehorn it in and expect people to go with it. You have to present a good idea and let it stand on its own merits.
There are many ways in which Sheik could be the main character of a Legend of Zelda game and easily make it superior to a traditional title. Liberal use of stealth easily comes to mind, as well as a variety of acrobatic puzzles, use of smoke/shadow, magic golden light mechanics, and lots of magic. All the ninja stuff, because Sheik is a ninja, and that is awesome. Link wouldn't do most of that stuff unless the stealth somehow involved a maze or fortress and getting thrown out of a palace or locked into jail by guards like always. He's a warrior type. Taking cover behind a steel shield and pushing around huge stone blocks is his thing. Sheik has to play somewhat differently, and the rest of the game should reflect that.
There has to be good reasoning and gameplay behind who and what the characters are. Having a gender swap where Zelda just puts on the standard adventure gear, and having to go rescue link whom somehow derped himself into jail/irrelevance is an obviously dumb shoehorn.
Yes, I would want to play a Sheik LoZ game.