Naruto dying isn't a bad idea, honestly, but it should be only after the next generation gets popular or loved. Problem with Dragon Ball Z was apparently no one was as loved or popular as Goku, or the editors wanted Goku (from what I heard, dunno if it's true), so Gohan never took up the mantle. If Bolt, Sarada, etc get great development, then Naruto and/or Sasuke dying shouldn't hurt the series so much.
I'm still convinced Goku should have stayed dead with his son taking up the mantle of hero and not becoming a pussy.