The 88mm KwK L71 and 75mm KwK L70 would actually be worth keeping even by the 50s and 60s and longer for light vehicles, although they could get so many improved components and ammunition that they would only stay Ship of Theseus-style. However by the time Germany could produce them again they have other foreign standards to use and evryone else had equivalent ammo/gun length standards to work with.
The one exception might be Czechoslovakia since they already built such ammo and guns during the war and could have good reasons to use those over the Soviet 100mm standard of the immediate postwar period (although OTL they just built higher velocity 100mms and called it a day).
The one exception might be Czechoslovakia since they already built such ammo and guns during the war and could have good reasons to use those over the Soviet 100mm standard of the immediate postwar period (although OTL they just built higher velocity 100mms and called it a day).