i think itachi will win, i hope there's an awesome battle and some sort of twist though, it will be lame if he just creams kabuto and forces him to release iwr by genjutsu. kabuto has some sort of trump card left so we have to wait and see. oro taking over kabuto and itachi would really be something though...
also, kabuto is a real idiot, he could have just waited until tobi and the allied forces cancelled each other out and THEN pulled out his summons, who would have stoppid him then? at this point all he has left is madara and kimimaro, he's bound to lose