I liked the idea that Maelfor came up with first. Link wished for Ganondorf to become good, and his intentions was that Hyrule would be a better place. Thats what he thought. But if a person should become good, he must do it on his own. Ingo for example, his evil where not removed by magic. The eivl would have to go soemwhere else. However, it could also manifest as its own being. Technically, it is not Demise that is incarnation, it is his hatred that incarnates, as i have understood it. Thus, Link could have removed Demises hatred from the body of Ganondorf. This could be a metaphysical Demise.