When Kakashi was dead, his father told him that it was something else destined for him. That destiny was this fight with Tobi!!! After this fight he may not live, since his eye is the only solid counter to Tobi's ST. I think that Kakashi is destined to leave naruto his sharingan and die protecting him. Bold theory but a bit farfetched. Hell, anythings possible when kishi's the author, right?