He's learning epic genjutsu hax because of how he sees and feels chakra? I don't know, just a wild guess. Sage Mode has an eye technique as a "side effect": Naruto can see the flow of natural energy. This seems like a good counter to the Sharingan. Naruto can potentially see through any genjutsu that doesn't mess around with natural energy. And if Naruto's chakra control continues to improve, he could create genjutsu that could trap the Sharingan, at least once, like how Jiraiya caught Pein.