Quote Originally Posted by Munsu
For all his powerfulness, that he looked like shit against Whitebeard and got scared shitless at one point makes me think he really doesn't have what it takes to be the final boss of the series.
At the moment Luffy doesn't have what it takes to take on the last boss of the series, but by the end of the series I can guarantee you he will. Just because Blackbeard doesn't currently have what it takes doesn't mean he wont have what it takes.