In terms of sheer power, Naruto has more than enough to take down Sasuke.
As far as I'm concerned:
Sage Naruto > Mangekyou Sasuke (or sage naruto is equal to Sasuke)
Kyuubi mode Naruto > EMS Sasuke
EMS simply hasn't impressed me to the point that I would say Sasuke could beat current Naruto, at least going on the basis of EMS Madara > EMS Sasuke. In his current form, Naruto single-handedly changed the course of the entire war, beating kage-level opponents with clones (the sort of people giving Sasuke a very hard time at the kage summit). Tbh, I really don't see Sasuke becoming stronger than Naruto again until/if he acquires the rinnegan.
The real challenge will be the emotional struggle involved; if the Naruto/Sasuke fight is to be the final battle, whilst it will obviously be close, the hardest part for Naruto will be forcing himself to take Sasuke down, not trying to compete with his level of power. If they do have a fight to the death and the manga ends with the fourth war, the following will likely be the case IMO:
Test of power: Tobi
Test of will/emotion: Sasuke
If the manga isn't ending anytime soon and the two of them fight, it will probably be a really epic fight but with no evident victor (or with Naruto not being able to bring himself to do it, etc). And you never know, after losing to Naruto Sasuke may yet realize the error of his ways and go back to team Konoha...anything's still possible at this stage...