Konohamaru, hes stated it was his dream since day 1 and thats why hes rivals with naruto, it'd be a slap in the face to the characters and fans if he didn't end up becoming hokage after naruto dies/ steps down.
'The one with zero percent chance is kakashi, he didn't even want to hokage in the first place. I believe he only became the 6th as a favor to naruto, as a buffer between the time tsuande steps down and naruto is ready to take over.