What's your point obito can send a entire portion of him to kamui dimension plus ms obito has a spare sharingan to use izanagi that last 10 minutes give it up dude itachi can't win against obito.Bruh omg thats cus he sent that part( his shoulder) to the other dimension lol. If his whole arm, or leg, or head gets amaterasu on it how will he fight? Hes done. Obito has no way to get rid of it. Two ms sharingans are better than one. Manga established that when both kakashi and obito used them together.