Shiryu will destroy it for good ?
Zoro definitely have a special power in the left Eye, Oda will reveal his fonction in due Time.
Well, I might be wrong about the character for who Oda is saving the eyepatch.
If it is Luffy instead of Zoro, forget what I said.
If it is Zoro, then the only way he gets it is if he actually gets a serious injury on that eye.
And I think it was happen in the final war so not sure who would do it, too many ppl will be present there.