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In my opinion blackbeard will arrive in wano just when kaido is on the brink of failing against luffy and gang and will take kaido's dragon fruit which will give teach 3 of the strongest devil fruit abilities that exist rn and then he will set out to destroy the world cuz theories suggest that blackbeard is pluton itself
then he will destroy sunny which will outrage franky and the angered franky will somehow reveal that he never destroyed blueprints for pluton and he will make pluton for luffy, then they will recruit shirahoshi and take vivi back in the group and then take on BB.