Interesting. Obito would fit since Kakashi is his teammate, and that would relate to the whole sharingan-eye of Kakashi's ... but when did Obito die again, I forgot .. or have they told us? If Obito was killed by Itachi, when Sasuke was already old enough to know Kakashi, wouldn't Sasuke have related differently to Kakashi during their genin training/etc?

Seems more likely from Kakashi's talks in the past, that Kakashi lost his team on some dangerous mission, instead of losing one to an inside assassination/extermination rampage.

Sorry, sort of a stream of thought post