Thoughts:
1) Sasuke clearly has the advantage, even this late into the fight. Naruto can barely stand, and he cannot form Rasengan. Sasuke by comparison uses Amaterasu and then uses Rinnegan to absorb the kyuubi chakra. Naruto's majorly dead here unless the TB send him some juice ASAP. Nardo cannot form Rasengan and can no longer move fast enough to dodge Amaterasu. Plus Sasuke just formed Chidori.
Naruto: Can barely move, or even stand. Cannot form Rasengan or dodge Amaterasu.
Sasuke: Can form Chidori. Can use Amaterasu. Can use Rinnegan to absorb kyuubi juice. Kyuubi is out of juice. Sasuke has energy from the TB, plus a possible trump card from Hashirama (what was that jutsu ?)
2) Base Sasuke is now confrmed as stronger than Base Naruto. Check this panel. Four shots of Naruto getting punched in the face, two of Sasuke. Base Sasuke is strong, smarter and faster than base Naruto.