This creates something of a problem, and I'm not sure how it will go. I see a handful of possibilities, none of them seem good for the story:
1) Izanami was activated and works. Itachi forces Kabuto to release Edo Tensei, but not before saying a few last inspirational things to Sasuke. Sasuke, moved by his brother's words, Sasuke AT LEAST becomes a neutral party in the war, possibly a full-on good guy. Edo madara disappears, the manga becomes the World vs Tobi. Tobi is outnumbered and loses without any kind of epic final battle.
2) Izanami does not work. Itachi says what he needs to say to Sasuke and his soul finds peace before Kabuto can complete the stronger binding. The fight becomes Sasuke vs Kabuto. Either Sasuke defeats Kabuto in a rage, or else he escapes somehow (possibly saved by the white Zetsu spores on Kabuto, like has happened in the past). Edo Madara is freed from control and is effectively immortal and uncontrollable. It's hard for me to see how the good guys win the fight UNLESS Sasuke becomes a good guy and helps the Kages to defeat Edo Madara while Naruto and Bee fight Tobi.
3) Izanami does not work. Itachi is captured by Kabuto and turned back into a killing machine. Now it's 2 vs 1 and Sasuke will either have to escape (again, possibly with help from Zetsu) or will be forced to unlock higher powers in himself (full EMS control, tap into huge chakra reserves in his rage, or unlock the rinnegan). Kabuto, Edo Madara, Edo Itachi and Tobi form an almost unbeatable team. The only way for the good guys to win is for Sasuke to become good and help in the fight.
4) Izanami does work. Kabuto is forced to release Edo Tensei, but not before Itachi says some heartfelt things to Sasuke. Kabuto does not die, but instead the fight is broken up by Tobi/Zetsu. Kabuto, Tobi and Sasuke are the core bad guys and are able to fight a mostly-even battle against the good guys for some time, especially if Sasuke can unlock Rinnegan. Eventually, Itachi's words cause a change in Sasuke and he eventually is redeemed.
Some of these options seem like they would be bad for the story, either making the bad guys too week for a good final battle or making them too strong for the good guys to have any plausible hope of winning.