User blog comment:Xilinoc/Ch. 684 - The Blade/@comment-3430033-20160730000611/@comment-24769684-20160730011814

I'm pretty sure Kishimoto was able to end Naruto on his own terms due to the series' popularity. He just wanted to make it look cool by ending at a round 700, and perhaps he lost track of planning at the end which is why Naruto vs. Sasuke was so rushed (though I'm not sure I'd want to see MORE of that)