those who r saying that u need tsukoyomi and amataresu to awaken the susano,just based on the dialogue of itachi,should remember that was not kishi speaking the fact but a char. created by kishi stating things in his knowledge.
madara on the other hand said u need both eyes to awaken sharingan's true potential.up until now,madara only showed tsukoyomi [chap. 601-606] and susano.
obito is planning to become jubi's jin himself,and it would be stupid if he plans this knowing the plan is tsukoyomi and he doesn't even have a tsukoyomi.
ot- a susano with an ability to phase like kamui,yeah he would be totally op,even madara will pale in his comparison.think about what if he awaken his own rinnegan.