This could definitely be ZKK and if so, imo that would be really hype. But I'm also open to the possibility that it could be something else. Ryuma did defend wano from outsiders and the marines are trying to conquer wano. Perhaps Zoro could have a brief 1v1 with a navy admiral at the end of the arc. Something that parallels his "nothing happened" moment with kuma at the end of thriller bark.