If you've noticed how Oda develops secondary characters, it's not really the best. A lot of time, this development seems really forced.
For example:
Zoro going from no CoC to ACoC
Kid going from being irrelevant to 2v1ing big mom
Law somehow getting awakening between dressrosa and wano with no foreshadowing
Sabo becoming" flame emperor" by asspull
Chances are, Oda is going to use this same sort of forced development on Koby. He has to become an admiral by EoS somehow and haki is the most contrived power system in shonen; a system that exists for the sole purpose of allowing the heroes to spontaneously power up and win. So I see no reason why Koby wouldn't also be blessed by the asspull system that Oda created for this very purpose.
Koby has shown to be very haki sensitive. It's the main power of his that Oda highlights. So I'm guessing this is what Oda is going to do to make Koby an admiral. He is going to reveal that in Amazon lily, Koby awakened ACoC and was able to briefly clash with Hancock. This caused the marines to promote him straight to VA and make him a hero, as he is one of the only marines with CoC.
Then in the final war, he will eat a logia or a mythical zoan, allowing him to replace Kizaru or Ryokugyu once the WG is defeated.
For example:
Zoro going from no CoC to ACoC
Kid going from being irrelevant to 2v1ing big mom
Law somehow getting awakening between dressrosa and wano with no foreshadowing
Sabo becoming" flame emperor" by asspull
Chances are, Oda is going to use this same sort of forced development on Koby. He has to become an admiral by EoS somehow and haki is the most contrived power system in shonen; a system that exists for the sole purpose of allowing the heroes to spontaneously power up and win. So I see no reason why Koby wouldn't also be blessed by the asspull system that Oda created for this very purpose.
Koby has shown to be very haki sensitive. It's the main power of his that Oda highlights. So I'm guessing this is what Oda is going to do to make Koby an admiral. He is going to reveal that in Amazon lily, Koby awakened ACoC and was able to briefly clash with Hancock. This caused the marines to promote him straight to VA and make him a hero, as he is one of the only marines with CoC.
Then in the final war, he will eat a logia or a mythical zoan, allowing him to replace Kizaru or Ryokugyu once the WG is defeated.