I was just having this idea. We all know that the Shichibukai need a replacement for Crocodile because according to the Gorousei if the three powers collapse the world itself would fall appart.
At the current time it doesn´t appear as if they´ve already found a replacement. Laffite nominated Blackbeard as a replacement, but there hasn´t been a definite decision so far.
So I was thinking what if the Strawhats take down more Shichibukai before the WG actally makes a decission about a Crocodile replacement? I mean then the chances of the three powers collapsing would even be much higher.
And then it hit my like a bullet. Let´s say that in that at some point there would be only two Shichibukai left and the WG requires replacements badly. Wouldn´t it be an option to make the entire Blackbeard Crew Shichibukai then?
I mean if it would be like this that for each defeated Shichibukai we would be replaced by a new pirate from a new crew we´ve never heard so far, then actually this Shichibukai business could start all over again and again. And the Shichibukai would always work alone.
But if the Blackbeard Pirates would be Shichibukai then it would also mean that they would work together. It wouldn´t be like this that the Strawhats take down just one guy but they would have to fight five at once. It is inevitable that the Strawhats and the Blackbeards collide. And if it would happen that way then the balance between the three powers would collapse for sure because five Shichibukai would be taken down simultaniously. I mean replacing a Shichibukai one by one would somehow be an endless matter and the collapse of the three powers could be something that Oda wants to establish somewhere down the development of the story. It´s just an idea anyways. 
