just going to throw that out there. gai has broken his forehead protector so I don't see why it couldn't happen during the final fight with naruto and sasuke.
I don't have a clue on what it could do. I just think it'll happen for whatever reason. the sage compares him to his mother so at this point who knows.
lol he already has solo'd 3 reincarnations( hashirama, naruto, and sasuke) he would have solo'd obito but obito escaped because of kakashi's help and kakashi and his kamui is irrelevant to madara if it wasnt then kakashi would have attempted to hit madara with it but the truth remains the Godara is faster than both kamui's separately and is faster than them together if he uses rinbo but he doesnt want to destroy his rinnegan thats in obito's eye socket...the 8th gates is trivial to madara as well, gai is killing himself madara doesnt need to touch him and minato and lee saved gai's life twice so he died 2 times already...so technically yes he has beaten 8th gates+kamui+3 reincarnations....u hater