User blog comment:Ghmorello/Chapter 907: Game Of Empty Thrones/@comment-24850639-20180608153740/@comment-3507581-20180614043428

The thing about Kaido and Big Mom is that it's clear the Straw Hats' power and reputation escalated until they eventually got into the target of the biggest names in the pirate "business", so for a "no-name rookie" (I'm using the term loosely) to irk two Yonko in some way and these two Yonko to talk about him in a fairly cryptic way shows that Luffy's reputation as the "Fifth Emperor" does not suit well with the veterans.

And Shanks, like you say, is probably talking about Blackbeard if this means the Gorosei are the other side of the conversation. If Teach using the Shichibukai position to rise in power was not enough of a deterrent for the World Government to try to stop him (they even said only the other Yonko crews could do), maybe what Shanks has to say will be.

And yes... Lucci being part of CP-0 is not that impactful, but at least it means Oda has not forgotten him (and Kaku, but what about Kalifa, Blueno or Jabra?), unlike say, Enel, Kuro or Krieg (which I hope at least to make a comeback) and would foreshadow any role in the "final war". I think he is loyal to to the WG even if they tried to hunt him and his colleagues because in chapter 0 he was trained to be an assassin since childhood, so you could notice that experiences in that age influence the personality greatly.