It happened when many said it wouldn't. The US military adopted not only a new service rifle but a whole new cartridge, the 6.8x51 also known as the .277 Fury. The gun is solid, but the 6.8x51 seems like a huge step backwards and the US military has abandon the assault rifle in favor of a Cold War era type battle rifle.
Good discussion to listen to all those who suggest Pakistan should follow the same path with this cartridges.