With Jiraya and Orochimaru out of the picture, it is apparent that Tsunade may not have too long left (in my opinion). When (if) she dies, someone is going to have to replace her. The question is who will.
In my opinion, Kakashi is best suited for the title of Hokage. Not only does he have the most experience out of anyone in the village, he also is one of the few people in the village who can use Elemental Manipulation to the fullest. Having the Sharingan is also a big plus! He is currently the only leaf ninja who has the Sharingan and can use a technique that not even Itatchi could use! (No, Sasuke does not count since he left Konoha and has plans to destroy it)