bitcoin into the world's single currency seems very likely, but for the next five years is likely to occur only in advanced countries, because developing countries are very difficult to apply because developing country technology is still not supportive and has not been integrated with world finance, most likely developed countries will support the financial system a third world country is very likely to happen, and even then could be more than five years. but I am very optimistic that someday there must be a single currency in the world, and the currency of cryptocurrency is very potential for it.