These include geopolitical influence, political stability and the enforcement of the rule of law, as well as good political and economic governance. Only large economies generating meaningful network externalities possess international currencies. They must also be economies with deep, efficient and open financial markets where it is possible to invest without the risk of incurring large transaction costs or capital losses.
Eventually, once all these factors have been accounted for, the quality of economic governance and economic institutions and the ability to devise policies which support confidence in the external value of the currency can make the difference. Obviously, inertia in the international use of currencies is strong and sudden changes in their relative position are unlikely, barring very large shocks.