It may be farfetched but I think joker would be the best final villain after this arc he will disappear for a while to locate the ancient weapons
Lava admiral faces off with bb and luffy in a 3 way clash as the world watches except kid he busy beating up garp and sengoku. BB is knocked out fleet admiral reforms only to have his head kicked off by doffy who then uses some special item to kill him. Just when he tries to finish off luffy and destroy the entire island BB absorbs the ancient weapon and immobilized doffy allowing luffy to knock him in a pit of lava with BB. BB utters some crap about dreams and destiny luffy is now deemed king
Then again luffy and kid may have the final fight who knows lol
Lava admiral faces off with bb and luffy in a 3 way clash as the world watches except kid he busy beating up garp and sengoku. BB is knocked out fleet admiral reforms only to have his head kicked off by doffy who then uses some special item to kill him. Just when he tries to finish off luffy and destroy the entire island BB absorbs the ancient weapon and immobilized doffy allowing luffy to knock him in a pit of lava with BB. BB utters some crap about dreams and destiny luffy is now deemed king
Then again luffy and kid may have the final fight who knows lol