manga that the split bloodline meansthe true power of the so6p can't be fully realized in either one by itself. Uchiha can't sustain rinnegan without the stamina of senju or uzumaki. How can you say even if circumstantial in itachis case, he is better candidate than any for. Awakening rinnegan after madara. Do you deny that? He has completed thus far all known sharingan tech sans ems. Perhaps once he obtained ems he would have all the ingredients but not completing that allowed him to live as long as he did.