I wanted to make a theory about Dragon, and hear other theories about Dragon.
Dragon must be a close friend to all current Yankou as it was noted that Dragon told Ivankov that the world balance was beginning to shift after WBs death. This could be a sign that the Yonkou currently know of Dragon but they are working with Dragon to change the world.
Remember in the beginning at East Blue, Luffy was aboard of Shanks ship, why exactly would Shanks have protected Luffy if he didn't know more about Luffy from the very beginning?
I believe that Dragon must be more powerful then all of the Yankou, and his Nakama are more powerful than most pirates in the world?( Kuma, Ivankov) Kuma was Shichibukai that wiped out Luffy's enitre crew after they fought Moria.
I sense another War will happen against the Revolutionaries vs The world Government based on what Dragon said after WBs death.
Also a far fetched idea, Could Don flamingo be a Revolutionary because Don Flamingo asked Croc to join him in making of a New Era, highly doubtful.
Just a Theory.