Bakkin is a fodder, she probably got captured, which is why Weevil was able to be manipulated by Buggy. Mihawk probably joined, not because he actually acknowledges Buggy as his superior, but because he doesn't want to be chased around by marines and would much rather have the fodder of the buggy pirates take care of marine fodder for him.
As for hancock, idk. I think she would rather be with Luffy. I think she might get captured and taken back to be a slave in mariejois. Then Luffy will have to save her and in doing so, become the breaker of chains like Nika was.