User blog comment:Uraharattack/Finally Caught Up in the Manga. Prediction Time!!/@comment-58.166.115.66-20151108055729

My theory is that the Straw Hats will fight the Blackbeard pirates on Raftel in the penultimate arc.

Robin will find the Rio ponyglyph and reveal the secret of the lost century, which will be the trigger of a world wide conflict against the world government for something that happened in the void century. I have a feeling that not all pirates will side with Luffy and not all marines will fight alongside the WG (Coby, Smoker and Fujitora fighting alongside the SHs). The final villains will be the Gorousei.