IDK if Kakashi will become the hokage once again. But Tsunade seems like she's not going to make it, so it's either him or Naruto. Though, I personally think that Shikamaru's father should become the hokage if Tsunade dies.
Its not really about strength you have to be intelligent as well and I think naruto's feeling get the better of him and that could be dangerous in a situation where he has to save Konoha. We didnt see other Hokage's being filled with rage/Hatred and fighting blindly all of the Hokages had a clear mind what ever situation they were in. I don't Naruto is intelligent enough yet he has to make Decisions that will benifit Konoha and hard decisions aswell. I think he is too young for that atm.
My opinion exactly. Either Naruto ends with one of those two as the 6nd Hokage or Naruto story continues or some fillers that shows how Naruto finally acheives his goal.