SPOILER

In episode 1006 ten years later after Naruto has become hokage he travels back in time using his ninja jitsu he calls the Time Travel No Jitsu!

He travels back to said incident and rescues Haku and Zabuza from their sad defeat. Unfortunately he is unable to arrive in time due to the imperfected carrying out of his Time No Jitsu so haku still dies.

This causes him to use the Bring back from dead no jitsu which revives haku and they all live happily ever after. Somehow Sakura dies and many people rejoice.

Sakura is replaced by a chick who can actually do stuff and an unfortunate incident occurs. Naruto from the past and naruto from the future give each other a high five causing the universe to implode.

Thus the series ends.