Ah, where shall I begin...First off Danzou's place in the naruto universe is of no use to the current plot line. Danzou has been a whole other sub plot throughout all of Shippuden so now of all times he finally is fighting and its up against someone who could kill him. Seeing as the Story line is a already complicated enough this situation with Danzou would provide the perfect outlet to end his "plot".
With that being said moving on to Itachi and Sasuke, it would seem that assuming that Itachi has come back reborn it would ruin Madaras Plans and he'd be forced to kill Itachi or take Sasuke from him. Where as is if Itachi was only a temporary embodiment he'd leave Sasuke twice and that may be where Sasuke falls deeper into darkness, which is what Kishi said would happen anyways. So either way it doesnt matter how it Itachi is back or if he even is he'll be taken out or forced back in some way. And Danzou is destined to be dead soon whether he has 10 lives or 1 he'll most likely die so his abilities don't really matter.
I think that out of the two Itachi theories I've stated that niether prove true. I think Itachi simply implanted his summoning animal and shadow clone technique within Sasuke as with every other technique we've seen passed on to him. Sasuke is probably finally testing out Tsykuyomi, for it seems that all he's been doing is testing out new abilities and what better way than to do it on a man he hates.
But that just my opinion
Im probably wrong but we shall see, no?
