Whats wrong with sasuke, is he looking for more beef. When he says there is greater threat than kaguya, how many naruto fans will go wild. Sasuke is smart he wouldnt say something out of whim he would have proof or know something. When i first saw kaguya she didnt seem so badass. Even madara appeared more badass than her. I felt kind of sorry for her cause her own children turned against her. Even though they say she is a heartless cruel powerseeking ******, there was compassion in her, she was crying when she saw naruto and sasuke who reminded her of her children. If she was heartless, why would she cry. From watching that battle, i could see kaguya really didnt have intentions of killing naruto and sasuke she just wanted their chakra. Its only when things got serious, she tried to cause her plan was failing and needs to carry it out. Being the most powerful being, why would she go through all this to build an army when everyone is literally dead when she succeeds with her plan. Unless there is a greater threat? Kaguya stopped wars and brought peace she even said she wanted peace. So i think kaguya was never really the threat.