Spiegel

Why not? Not saying he definitely will because we don't know how much the upper levels of the Marine have changed, they might have gotten stronger or a lot more strategic with their approach against pirates. Luffy now isn't a mere rookie anymore, he's experienced tragic losses, under went through the hells of Impel Down, and the chaos of the a war. Jimbei helped reshape Luffy's purpose in life and Reyleigh helped in training to control his resolve through the training of haki. Two years later we see a way more confident Luffy with the potential to go toe to toe with an Admiral given how easy it was for him to one-shot K.O. a Pacifista. Luffy is trying to be the Pirate King, why would it be a bad thing if Luffy were to go against even with an Admiral? I'm not saying that he can take on all three at once.

True. But a lot can change in two years, Luffy, Sanji, and Zoro are living testimate to that. Sure Smoker is weaker compared to other Logia users, well he was seen to be in somewhat of a stalemate against Ace back in Arabasta but they weren't even going all out. Smoker's disadvantage just like Luffy was lack of haki, if he is to rise the ranks of the Marines (which he most likely will) he'll have had to develop the use of haki. Why? Because he is now stationed in the New World with even crazier pirates roam the seas.

Plus at first glance we have seen certain devil fruits looking "weak" or "useless" in the beginning but that have been known to improve with training just like Luffy's Gear 2 and Crocodile enhanced use of his sand abilities to cut and absorb.

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"Inherited will, the destiny of the age, and the dreams of its people. These are things that will not be stopped. As long as people continue to pursue the meaning of freedom, these things will never cease to be!"
-Gol D. Roger

*Ex-Kakashi87*