I'd actually imagine Luffy and hancock having either one girl or one boy, but I'd like to think it would be three kids. First would be a girl named violet who is like hancock but more silly like her dad. 2nd be a boy named ace like his uncle Ace who has his sleeping when eating habit and Luffy's appearance. 3rd be a boy named Sabo after luffy's other brother who is goofy like luffy, but more mature and smart. I'd imagine them with wild kids, but they'd be able to handle it as the pirate king and pirate empress.