...But...Danzo already took the title of the 6th Hokage, even if it was just for a small time... It's too late for Naruto to be the 6th
Lucky #7 maybe?
Ah, but Danzo never officially became the Hokage. The Jounin hadn't voted him in, and he had been hoping that his acceptance as part of the Ninja Alliance would force the Jounin to accept him as their Rokudaime Hokage.
Unfortunately for him, Sasuke showed up. So the spot for Rokudaime remains open for Naruto.