Eight-inch destroyers and naval fire support

What if the U.S. Navy had standardized on 8-inch guns for cruisers and destroyers instead of the 5-inch gun?

Widespread 8-inch destroyer guns would change fire-support logic, make Iowa-class retention harder to justify, and could push allies toward heavy 6-inch or 8-inch surface guns.

A postwar U.S. move to 8-inch destroyer guns could spread to allied navies. If destroyers and cruisers carried many such weapons, the fire-support case for retaining Iowa-class battleships and their 16-inch guns would weaken. Britain might instead pursue a faster-firing 6-inch weapon. Either heavy main-gun path would leave room for 3-inch secondary batteries, changing later arguments about air and drone defence.