The foreign exchange or forex market is the largest financial market

The foreign exchange or forex market is the largest financial market in the world with a daily volume of over $5.1 trillion. The demand for foreign exchanges arises from international trade, tourism, government spending, and hedging and speculation.
During recent years, there has been the rise of crypto currencies, such as bitcoin, which could potentially become "global currencies" and replace national currencies.
Could bitcoin and other cryptocurrencies eventually replace national currencies? Why, or why not? What would be the advantages and disadvantages for the individual countries? What are the advantages to consumers?