Now that would be funny, before they leave the hokages could say they left all the knowledge to become the sage of the six paths in one piece and that could be the start of the new ninja age.
What I find really weird is that they don't seem to be any other kage level ninjas in the entire army. You would think a village would have a goodly number of other ninjas to replace their kage if they died in battle. The leaf seemed to have always had an abundance of ninjas of that level Hashirama, Tobirama, Hiruzen, The Sannin, Minato, The Uchiha etc but the other villages seem to have a real lack of quality shinobi. Subtract all the leaf nin that were involved in this battle and all the other shinobis combined would have been crushed already.
Why did you come back to it. I came back because Itachi was revived and I was hoping to finally see Tsunade die after being teased so many times.