How do you think Sasuke will react when he discovers his old sensei has developed the ultimate Sharingan? Sasuke, as we know, tried to attain that eye by means of killing Naruto, but couldn't do it. Do you think he will be angry that Kakashi found a possible alternate way to get it which he's never found out, or maybe just surprised in a amused way? It would be funny if he thought, "Gee, if I would of hung around that guy, I probably could have gotten MS by now." I guess his reaction all depends whether or not he has the Mangekyou himself. With Orochimaru, a genius at jutsu and the like, and his own skills, Sasuke could have gotten it by now.