Is it 100% confirmed it's only going to the jinchuuriki battle?
It's not. It was only hinted at. But judging from the characters revealed, Naruto's Bijuu Mode, KB's forest clearing spin, Kakashi's awakening action (with the Raikiri clothesline), and Gai getting Asakujaku back (he used it in the fight while Kakashi did his thing), it's a safe bet it will.
Ah. I wouldn't too surprised I suppose. It would be nice if Kabuto got sage mode, and of course if it went slightly farther that'd be more for Madara to have in his arsenal.