Hrrm...no I haven't given it much thought, but you have a point. Gaara becoming Kazekage and then getting captured by akatsuki has kind of killed a lot of the luster assosiated with the kage position. So if Naruto becomes kage it's like "well, he has a demon, got really strong, gaara did it, so...yeah, whatever." It would be far more interesting to see him not become kage at all, and currently things are set up pretty nicely to push things in that direction.