I predict that Luffy might use Bellamys technique and improve it further in a future fight.
I think the future fight is the current fight Luffy vs Katakuri.
Hear me out guys there is a lot of stuff I will compare, so your first reaction might be “wtf is he talking about?”, but it might sound logically after all.
Let’s first talk about Bellamy’s devil fruit power, the Bane Bane no Mi (Spring-Spring fruit).
His abilitiy is to transform body parts into springs and so he can jump off from the ground with high physical power.
He can increase the physical power by stacking it. He achieves this while keeping jumping off walls and objects, so he becomes faster and more powerful by time.
This technique is called the “Spring Hopper”. Potentially Bellamy’s strongest attack.
He used this attack back in Jaya and improved it on the second encounter with Luffy on Dressrosa.
Let’s talk about the origins of the “Spring Power”.
The metal springs are made of metals with the highest grade of “elasticity” known.
So the power of this devil fruit is based on elasticity.
Let’s compare Bellamy’s devil fruit to Luffy’s…
You can argue that the Spring fruit might be the inferior version of the Gum fruit.
-Rubber has the highest elasticity among all materials.
-Spring steel has the highest elasticity among steels.
Also rubber has alot of other properties, like you can blow air in it and such.
What about the Mochi fruit?
Mochi is known for having the highest elasticity among food, especially sweets. At this point i must admit that a raw squid will have much more elasticity than mochi. xD
Similair to the springsteel and rubber, mochi is going back to its original form.
Other than springsteel and rubber you can put something inside the mochi and take it also out similar to how Katakuri keeps a spear inside him. (pocket dimension)
All in all we can argue that Katakuri’s fruit is the superior version of Luffy’s one, proven constantly troughout the last chapters of the Whole Cake Island arc.
Mochi still has not higher elasticity than rubber, also if it comes to its “mechanical power”.
Mochi just has a higher versaitility of other attributes than rubber.
So with rubber having the higher elasticity, ESPECIALLY IN GEAR FOURTH, there might be a chance for Luffy to get out a superior attack than the ones of Katakuri.
SOO, WHY SHOULD LUFFY LEARN AND IMPROVE BELLAMY’S ABILITY?
As Oda showed us Katakuri is mimicing Luffys attacks one by one and he also is IMPROVING them.
There is no chance for Luffy basically to copy any attack of Katakuri and improve it on his own way. But what we know is that Shonen characters might adapt their fighting styles and abilities from former key enemys they fought in the past.
One of this key enemies might be Bellamy who turned out to become an ally.
Bellamy also fought against his superior fruit version, the Gum fruit user Luffy!
And right now Luffy also fights against his superior fruit version, the Moch fruit user Katakuri!
So I really would like to make a connection of those both fights.
Why else should Oda highlight Bellamy in the New World and bring back his final technique?
With an IMPROVEMENT!
So inferior abilities ALWAYS leave space into IMPROVEMENT!
Yes it makes sense for me for Luffy to adapt this ability, together with his Boundman and create his own superior version.
This in my eyes is a technique Katakuri will never be able to improve with his mochi powers.
So how will this technique most likely look like?
Luffy might go in Gear 4 to gain maximum elasticity, and he would jump off the narrow passage of the mirrow world.
Luffy might gain speed and power meanwhile and Katakuri won’t be able to track him down.
Meanwhile the rubber of Luffy’s body will rub with the air to create fire surrounding Luffy.
Luffy will enhance his Hopper ability with fire, which I predict is the counter to sweet related Paramecia devil fruits.
He will choose the right moment to deal the final blow to Katakuri which he won’t be able to see coming.
How ironic would it be to adapt the technique of the inferior devil fruit to beat the superior one?
This would fit into One Piece and it would give the fight of Luffy vs Bellamy a lot more sense.
Luffy adapts with the people he meets and fights and that is his way in gaining power.
*Theory by Rej Discussions