Somehow itachi will keep his promise and then he will disappear. Before stopping edo tensei he stalls kabuto for sometime and he will speak with sasuke.
You people forget there is more than one way to end edo tensei... itachi will probably talk to sasuke and have some emotional conversation, achieve closure and disappear.
Yeah, but that's why Itachi will turn it off with Tsukiomi. But I don't think Itach will die though because he severed all connections with the Edo Tensei. Otherwise, Kabuto would've just unsummoned him after he broke the control with Amatsukiami... :shrug:
Perhaps he cant unsummon just one edo. Cancelling the tech will unsummon all the edos he summoned.
And K.A only cancelled the effects of the tags Kabuto was using to control him. He's still bound by Kabuto's will to this world, which is why he is still able to regenerate.