A 5.3-inch US dual-purpose cruiser for carrier war

Would a US 5.3-inch anti-aircraft gun have blurred the line between light cruiser and carrier escort?

Yes. It could support a Dido-like American cruiser or a more heavily armed Atlanta-like escort, with air-defence value that could outweigh the six-inch gun's advantage in surface action.

A proposed US 5.3-inch dual-purpose gun raises the choice between mass-producing six-inch cruisers and more powerful anti-aircraft escorts. It could make a Dido-like American design possible, or give an Atlanta-like ship heavier armament. In the Pacific-war comparison, the six-inch cruiser's advantage depends on surface engagements that occur less often than its designers might want. Its heavier shell would also help against shore targets, but the difference is judged insufficient to outweigh the escort's air-defence value. The preference for the dual-purpose cruiser follows the expected balance of missions in a carrier war.