Gear 2 augments Luffy’s blood to increase base speed.
![](https://www.opfanpage.com/wp-content/uploads/2020/06/5426285-4681501-one-piece-luffy-gear-second.jpg)
Gear 3 augments Luffy’s bones to increase mass and attack power.
![](https://www.opfanpage.com/wp-content/uploads/2020/06/Gear_Third_Infobox.png)
Gear 4 augments Luffy’s muscles to increase base speed, attack power (Bound Man), defense (Tank Man) and attack speed (Snake Man)
![](https://www.opfanpage.com/wp-content/uploads/2020/06/maxresdefault-49-1024x576.jpg)
My theory is that Luffy, inspired by seeing Kaido in his dragon form, will develop a Gear 5 that will allow him to reshape his skin into scales and harden them with the advanced form of Armament Haki exhibited by Katakuri.
![](https://www.opfanpage.com/wp-content/uploads/2020/11/EfZPuiBVAAE95SD.jpg)
![](https://www.opfanpage.com/wp-content/uploads/2020/06/Katakuris_Flame_Haki.png)
![](https://www.opfanpage.com/wp-content/uploads/2020/11/main-qimg-6e5c68f8c6015333b7f2749982c66da0-1-1024x349.jpg)
These scales will allow his body to stretch while maintaining an impenetrable defense.
![](https://www.opfanpage.com/wp-content/uploads/2020/06/21369456_1837891959559287_1813878696727067026_n.jpg)
Adding the blood flow of Gear 2 to the mix could interact with Armament Haki at high speeds like a full body Red Hawk, setting his entire body on fire.
*Theory by cntoruga