Naruto can regrow body parts why don't people understand this
I feel like Sasuke wont have a arm though it be lame if he had only one arm
They won't need zetsu. Tsunade was torn in half and was able to be healed just fine. They will probably use the same technique to re-attach each one of their arms.
Well reattaching body parts does seem to be plausible. But have you thought about the fact that their hands/arms are probably completely destroyed? Doubt they will have Tsunade reattach their hands back.