Itachi isn't as strong as a Hokage. The 3rd wasn't really hokage really. More liek a replacement so was the 5th. THe 3rd's time apssed. In his prime Oro can't touch him or the other sannins, so he can beat Itachi. The 4th could most likely beat him also. Tusande is a replacemnet for the death as I said and she isn't a fighter. The 1st and 2nd who knows if he can beat him. Plus He might not want to be hokage by the way. The otehr hyuga's don't even go to the academy.