The reunification of the currency is certainly good, but this is hard to come by because it means that all countries on earth have an alliance or just one country left, just like the EU. The former approach is basically impossible because countries have different views Different habits, and then one, for the time being, every nation has such abilities.
It is hard to have united currency in the world. The currency represents the economy of each country. At present, the difference between the economies is quite large. Many countries will not accept the use of the same currency