it won't end with naruto becoming hokage. it'll end with a huge battle between naruto and sasuke. sasuke.

then a year or two later, a new series will come out. called like... naruto v. where naruto and his friends are all older. starting off with a story like sakura being confronted --after becoming an iruka lvl genin teacher for a few years-- by sasuke, who is returning to town to check up on things, (he has evil plans we don't know about! oo~h!) then kakashi or someone arrives after hearing some commotion and sasuke fights him. sasuke could clearly win, but chooses to retreat instead. he returns again a little while later for some spooky reason and is involved in a huge battle with several top ninjas of the town including possibly aburame shino (yes!) but before sasuke can claim any lives or anything, Naruto returns saving the day. no one has seen naruto since the big battle that ended the first series. many thought him dead, but really he had just become a wanderer learning various skills in the various countries. like wind and sand and stuff. now he's returned because the 5th hokage is getting old and she alone knew of his whereabouts. she sent for him so he could return and become refamiliar with the town. he intends to become hokage, but sasuke has other plans. ...sasuke? or orochimaru...

of course, that would recquire sasuke to be dead for orochimaru to take over his body, and that totally would piss off an annoying percentage of japanese fans, so it won't happen.