Why did Itachi say that he needs to get someone's MS to get EMS while Sasuke only had a normal Sharingan? In the fight between Sasuke and Itachi, Itachi said that to get Eternal Mangekyou Sharingan (EMS), he must transplant his brother's eyes that have to be Mangekyou Sharingan (MS). However, Sasuke didn't have MS yet.

So, even if Sasuke did get his normal Sharingan eyes, how could he get the EMS?
Because he actually didn't want them. He was trying to relay that information to Sasuke before his death. He gave that information about EMS to Sasuke so that Sasuke could obtain EMS after his death if he wanted.

Plus Itachi was on the verge of blindness. So even if Sasuke had normal sharingan Itachi could at least have sight, that's a good excuse.