Honestly the more I think about Sasuke should have been the final opponent of the series, he should have had a story arc more like that of Harry Osborn in the Sam Rami trilogy. Be Naruto's enemy for a bit have a fight, learn he was wrong
and help him in the final battle to redeem himself. Whether or not he dies like Harry I think is up for debate.
I like that. Or show him starting to be like that over time, how he feels bitter and empty even after "beating" Itachi because while he hated him for the massacre of their clan AND the attention he got from their father, we know Sasuke loved and admired Itachi, wanting to become a great ninja like he was. So I figure that "beating" Itachi would get Sasuke to realize his hate and jealousy are what motivated him most of all, which could be like what Harry realized when Bertrand told him what really happened to Norman near the end of Spider-Man 3, and how Harry had his chance to redeem himself, especially since he was so misguided in his anger at what happened when he learned Peter was Spider-Man, supposedly killed his father, and the fact Peter while bonded to Venom came at him for payback and ended up scarring him too.