Interesting chapter indeed. Here's my thoughts:
I think Black Zetsu's identity has been further elaborated here in this chapter. We initially knew that Madara is the one who "created" Black Zetsu meaning he manifested Black Zetsu (as well as White Zetsu) out of his will using both Senju and Uchiha's DNA into flesh. Well, at least, that's what Madara thought. But in this chapter, Black Zetsu said, "My will is Kaguya" which means Black Zetsu is superior to Kaguya (just like when Madara thought he's superior to Black Zetsu), which should literally mean that Black Zetsu manifested Kaguya out of its will into flesh for some purpose, or that Black Zetsu manipulated Kaguya to do what Kaguya did (as told by the Hagoromo). So what does it mean? Note that Hagoromo told that Kaguya came from somewhere faraway to this planet and eat the fruit of the Shinju tree. So how did Black Zetsu manipulated Kaguya then? Well here's my take.
In correlation to the story of the Bible in Genesis of how the Serpent tricked and manipulated Eve to eat the fruit from the tree of good and evil, Black Zetsu manipulated Kaguya into eating the Shinju fruit. Where Black Zetsu comes from, we don't really know but it's certain that it is something that capable to manipulate even someone like Kaguya. Do you folks think this theory is plausible?