I just want to note that the 4th hokage is very dead...that bs that the hokage said about the two souls being locked in an eternal battle was false. when naruto talked to the kyuubi inside him after jiraiya threw him over that cliff where was the 4th hokage that should have been fighting the kyuubi?
thats why i believe that naruto is the reincarnation of the 4th. By sealing himself in naruto and the kyuubi within himself, the 4th sort of found a loophole that allows him to live again while still keeping the kyuubi sealed away.