Izanagi can only be used by those with the genetic traits of the Sage of the Six Paths. The Uchiha, descended from the Sage, are able to perform Izanagi with their Sharingan. Danzo isnt a descended of the sage so just havin the sharingan he couldnt do it he needs the dna so he got it from hashirama cells along wit wood release to increase his physical energy. I never said sasuke learn izanagi so who knows.
do you realise how rediculous you sound? Your argument is that the uchiha have senju dna already. Based on that premise, the senju and uzumaki have the potential to unlike sharingan because they share trace amounts of uchiha dna...see how stupid it sounds flipped in the exact opposite? Also, just because he saw danzo using it, and even if he related it to the name IZANAGI, that doesnt mean he can use it. Check the databook info on the sharingan it clearly states that the only things it cant copy are bloodline techs and must have the chakra levels to complete it. Even if izanagi is a bloodline tech of the uchiha, he must still be taught in its use, he cant simply look and copy because it doesnt use any visible action to activate.

