Not every Ninja is related to Kaguya. Just the Uchiha, Senju, Uzumaki and Hyuuga (We presume Hyuuga). Hagoromo did give like everyone the ability of Chakra through Ninshu. That's beside the point though.Yes, you did, thanks.
I knew this thread could bring a nice discussion, since Kishimoto has not yet developed this subject. I just don't agree with you about having to be an Uchiha, because, somehow, almost every ninja end up being Kaguya's related.
The thing that everyone here seems to agree, is that Naruto and Sasuke are the last ones. There wont be more Indra/Ashura reincarnation after this, since their job will be 'done' and they will, finally, rest in peace.