Pacific combat would decide the County-class cruisers' future

What would replace the Town- and County-class cruisers after this war?

Towns would remain in service, while combat performance would determine whether Counties were modernised or eventually replaced by very large six-inch cruisers.

The Town-class cruisers are still near the beginning of their careers in 1939, so they would remain in service for decades rather than receive an immediate replacement. The County-class question is less certain because London was already undergoing a major refit. Whether the remaining ships receive similar work would depend on how useful eight-inch cruisers proved beside six-inch ships in combat. If the heavier gun offered little extra value, Britain might eventually prefer a much larger six-inch cruiser instead of continuing the traditional heavy-cruiser type.