It's just like what Chinjao said, there will be many kings fighting to be the pirate king. He def have to be yonko level to be able to even fathom the thought of being the pirate king. Black Beard is waiting... lol
The last page on Ch 361 is why I love this manga, oddball as it is. His 'rival', his 'hero', and he's just grinning and having fun. Really makes me miss playing sports, when it wasn't about fame or money or winning...just playing.