The answer is really simple, she has the byakugan, but no curse mark the Hyuga branch family has, so all they need to do is somehow get her eyes then kill her... I know that Kishi is going to either give all of team 7 power-ups, or they're gonna team up with Tobirama, Hiruzen and Minato (Hashi can't really do anything ATM) and defeat Kaguya with team-work, but still it would be pretty cool/funny to see Kaguya be killed like that xD