The Mogami class was designed so its original 6-inch armament could later be replaced by 8-inch guns. That planned change shows that Japanese designers already understood how to build a treaty-era hull around a wartime upgrade. The same principle could have been applied across more ship types and capabilities. Interwar arms limits did not eliminate the option of planning ships for later changes.
Notable Point · 49:09-49:32
Mogami and treaty-era upgradeability
Mogami's planned change from 6-inch to 8-inch guns shows how a treaty-era hull could be designed around a later armament upgrade.