What happens when missiles run short

Could HMS Belfast, fitted with modern close-in weapons, have been useful during the Falklands War?

Potentially. Guns remain useful when missiles run short and bombardment requires fire that can pass over terrain.

A question about using HMS Belfast in the Falklands opens onto the wider problem of weapon endurance. Missile magazines can empty much faster than peacetime planning suggests, leaving a fleet in need of a weapon that can continue firing. Lasers may eventually help with line-of-sight defence, but they cannot arc fire over terrain for bombardment in the way a gun can. Larger twin 5- or 6-inch mountings may therefore return on future destroyers as navies prepare for sustained combat beyond a single missile exchange.