Why I say this is because:
Oda said in a SBS when someone asked him why he gave Luffy such a weak fruit, and he replied saying because wants Luffy to become the strongest with the most ridiculous ability
he also said this in another question
This shows that Oda has more plans for Luffy's power.
Also! We haven't seen the full potential of CoC and I truly believe that the haki which only 1-in-a-million have, does not only knock out weak willed people but does something else which is greatly OP, like how Shanks' CoC damaged a ship. Otherwise that wouldn't be precious. Furthermore, so many people believe, Roger and Shanks don't have DF's since they were/are just pure haki monsters. So why wouldn't the main character and future PK be a monster in that field.
Oda said in a SBS when someone asked him why he gave Luffy such a weak fruit, and he replied saying because wants Luffy to become the strongest with the most ridiculous ability
D: In the ONE PIECE of these days, all kinds of strong ability users who even Luffy can't compete with have been appearing, one after the other. In general manga and anime, I feel that the protagonist is established to be the strongest of all, but why did you decide to turn Luffy into a pretty weak-looking Rubber Devil Fruit User? P.N. Do your best Japan
O: Ahaha, that is true. It must seem like a mystery when you consider all the other strong and cool abilities. The answer is simple. I have picked the most ridiculous ability. If the protagonist were the typical strong guy, I doubt I could continue on with this for long. No matter how serious the story gets, Luffy is there to stretch and inflate. He always give me a chance to fool around. That's the kind of manga I wanted to write.
D: Now that so many Devil Fruit have appeared in the series, do you ever wonder if it would have been better to make Luffy eat a different fruit other than the Gomu Gomu Fruit? (P.N. Happy)
O: Nope. I absolutely agonized over this before the series began, but not at all since. I love the idea of a rubberman.
Also! We haven't seen the full potential of CoC and I truly believe that the haki which only 1-in-a-million have, does not only knock out weak willed people but does something else which is greatly OP, like how Shanks' CoC damaged a ship. Otherwise that wouldn't be precious. Furthermore, so many people believe, Roger and Shanks don't have DF's since they were/are just pure haki monsters. So why wouldn't the main character and future PK be a monster in that field.