Could Admiral-class successors carry 16.5-inch or 18-inch guns?
Short answerYes. Moving to 16.5-inch or 18-inch guns is accepted as a possible development.
NotesThe alternative is a larger development of the Queen Elizabeth idea, combining 28 knots with heavier guns. A 16.5-inch or 18-inch armament remains a possibility within this counterfactual. No final calibre or turret arrangement is selected.