While oda could technically just have zoro and sanji go the same route as luffy when it comes to strengthening their haki with powers like internal destruction or future sight i personally doubt he will
Luffy just developing it in a more linear fashion getting the most advanced form of armament with internal along with unlocking external
Zoro already having external armament (something he’s been capable of since daz) and instead of just advancing his armament further he got enma. A blade that strengthens his armament by increasing his output and overflow. Him being capable of king of hell mode because of his mastery of the blade
Sanji having the most basic form of armament but instead of specifically boosting it he stacks the toughness of armament with the toughness of his exoskeleton to develop ifrit jambe
I think that that pattern might also apply to their other forms
- Luffy more directly just upgrading his haki
- Zoro through mastering blades
- Sanji tied to his scientific upgrades
Even when it comes to conquerors it seems like it’s going to be the same pattern
- Luffy unlocking and better mastering it just because he’s naturally proficient at using haki
- Zoro unlocking it through his mastery of enma. Him even saying he’ll become the king of hell knowing that’s enmas nickname as well
- Sanji is extremely likely to unlock his conquerors when reflecting and embracing his germa genetics
Id even go as far to say zoro’s asura and sanji’s jambe might end up being related to their sword and genetics respectively?
Asura being a power connected to sandai kitetsu “cursed” strength.
Jambe being related to the drug sora took that helped Sanji keep his humanity