Danzo was evil, anyways. They should be thanking him. Good riddance.
P.S: I think Danzo might've even worked with Tobi if he thought it was for the "good" of the village.
It'll be a talk after they stop kabuto and have him captured, then they'll talk, and then Itachi will use genjutsu to make kabuto undo the edo tensei. I don't think Itachi can afford to break another promise to his brother, after all, he was the one who said he had something important to discuss after they're done with Kabuto. Or....he could break his promise and that'll make sasuke super mad and obsessed with killing everybody in his sight. Either way works.
I do believe if he didn't, most of the Shippuden story would have been for nothing. And with the message(s) Kishimoto is trying to convey, I find it highly unlikely that Sasuke would not return.