I agree, Sasuke Vs Naruto will definitely be the last fight of the series. Sasuke has been on the wrong path for the last 3 years, consumed by his hatred and delving deeper into the dark side. I think that this is the moment he has a chance to change back after reflecting on his actions, if he doesn't, he's destined to be evil and possibly a major villain. The blood drip, his eyes darkening, and that smile are possibly indicators that he's gained the mangekyou Sharingan and that will be his downfall unless he uses that to defeat Madara and overcome his clan's curse. Sasuke's fate depends on his next action after he wakes up.