I think killing Link would be terrible.That would totally change the Zelda series, and I think it would be for the bad. Replacing our green clad hero, Link? I ask you, what could be worse for the Zelda series than that? It would just ruin it for me, more than Link being able to talk. What would Zelda be like with no Link? I think that he's a perfect hero for the series, and I highly doubt Nintendo would do something like this. It would just scare too many fans away.
Of course, seeing spirit tracks has made me wonder. Ninty might actually do something like kill Link. They've already killed him in every way except in the actual story with that conductor's outfit.