If treaty destroyers displaced 3,000 tons

How would naval design change if the first London treaty allowed 3,000-ton destroyers?

Destroyers would become proto-Darings, and pressure to separate ship categories would raise cruiser, carrier, and battleship limits as well.

Regular destroyers would approach the later Daring class in size and capability, with enlarged flotilla leaders becoming almost light cruisers. Preserving meaningful category boundaries would likely push cruisers toward 12,000 to 15,000 tons, carriers toward 30,000 tons, and battleships toward 40,000 tons standard. A 40,000-ton King George V design gains enough margin to revisit a twelve-gun battery and other improvements.