I am not madame shersley but i could foresee what will happen to luffy when he becomes the pirate king.Open the spoiler to know my theory
SPOILERS
SPOILERS
In another 8 to 10 years when luffy finally becomes the Pirate king ,He will voluntary surrender to either smoker or coby .My personal choice is smoker cause he has been always after Luffy and he also has certain soft spot for luffy.More spoilers ahead
Luffy might even ask smoker or cobby to take care of his unborn child and history will repeat itself.More spoilers ahead
when luffy finally becomes the Pirate king,He would have found the one piece 
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