Naruto Chapter 387

[Rikudo]

With all the eye snatching going on, Kakashi better start running or else Tobi will pluck his left eye out when he see's that Kakashi have a MS.

[Assertn]

I don't think just "switching eyes" is the point to EMS. The process they're following has two effects. First of all, it's the act of killing your brother, which in itself has to be a factor considering that the requirement of killing your friend was for the first MS. Second of all, the demon behind Itachi/Madara shows two sets of eyes, which suggests that it's the combination of both pairs that creates the EMS, not just the replacement. Maybe there's a process to physically merge the eyes into yours or something....

[joker-kun]

I agree with Assertn completely. I think it requires the new eyes and the old eyes. Also as stated above, it might just be that people tried to gain the MS, but couldn't even after killing their friends, but when Itachi spoke of three being capable he meant present time didn't he? So who knows there could have been more in the past. It was probably well hidden and forbidden.

As for Itachi wanting Sasuke's eyes now his explanation has been very vague (thus the reason for so much speculation about this, and the above points.), but -I- think what it is is you need someone who is capable of gaining MS. Sasuke is definetely capable, along with his hate, but he was just too stubborn to kill Naruto.