It did conclusively demonstrate that hoary old maxim of military doctrine: you are best prepared to fight the last war. The "giant mess of unguided rockets" school of air-to-air combat pretty much ceased afterwards:
The Mighty Mouse was to prove a poor aerial weapon. Although it was powerful enough to destroy a bomber with a single hit, its accuracy was abysmal. Its spin rate was not high enough to compensate for the effects of wind and gravity drop, and the rockets dispersed widely on launch: a volley of 24 rockets would cover an area the size of a football field.
As a result, by the late 1950s it had been largely abandoned as an aircraft weapon in favor of the guided air-to-air missiles then becoming available. The Mk 4 found other uses, however, as an air-to-ground weapon, particularly for the new breed of armed helicopter. A volley of FFARs was as devastating as a heavy cannon with far less weight and recoil, and in the ground-attack role its marginal long-range accuracy was less important.