People argue that the next phase of money would be towards the e-cash system (which cryptocurrencies are the medium used). But this would take a significantly amount of time until it becomes implemented due to the economic discrepancies among countries of different financial state.
E-cash system? It is more interesting to discuss in the future if the system makes cryptocurrency as the medium used.
If bitcoin is adopted as a global currency in all countries then it is very impossible for now. Many countries prohibit it because it will disrupt the financial stability of the country and the world. This will be difficult to implement because the value is very volatile