Although I am no longer an Itachi fan (my heart belongs to Sasuke now), I still admire his power and recognize him as one of the strongest in the manga. Here's how I think a theoretical fight between Naruto and Itachi would go:
Naruto: I'm a lot stronger than before and with Kurama and his friends inside me, your genjutsu will no longer work!
Itachi: No longer work, huh? That is a belief that has been shaped by the false reality you live in, a mere illusion.
Naruto: Cut the crap! I'm finishing this now!
*Naruto goes into kyuubi sage mode and fires a lightning fast rasen shuriken that splits Itachi in half*
Naruto: That settles i-
*Crows appear*
Naruto: This is...everyone help me ou-huh?
Itachi: I've entered the realm inside of you...so they're all inside you now, huh? As I expected.
*Itachi goes into susanoo mode*
Itachi: Any last words, beasts?
Kurama: I'm just getting star-
Itachi: This is the sword of totsuka, I have now sealed you all. You've been allowed to roam for too long, I'm putting an end to it.
*the scene switches back to the real world where Naruto is lifeless on the floor. Itachi walks away*
END
Naruto: I'm a lot stronger than before and with Kurama and his friends inside me, your genjutsu will no longer work!
Itachi: No longer work, huh? That is a belief that has been shaped by the false reality you live in, a mere illusion.
Naruto: Cut the crap! I'm finishing this now!
*Naruto goes into kyuubi sage mode and fires a lightning fast rasen shuriken that splits Itachi in half*
Naruto: That settles i-
*Crows appear*
Naruto: This is...everyone help me ou-huh?
Itachi: I've entered the realm inside of you...so they're all inside you now, huh? As I expected.
*Itachi goes into susanoo mode*
Itachi: Any last words, beasts?
Kurama: I'm just getting star-
Itachi: This is the sword of totsuka, I have now sealed you all. You've been allowed to roam for too long, I'm putting an end to it.
*the scene switches back to the real world where Naruto is lifeless on the floor. Itachi walks away*
END