I wonder how much time has to pass to introduce this idea to real life.
Tens years, my friend. However, IF even it happens, people will return soon to use traditional money as well. Simply cash is very convenient, and no Internet connection is required.
Well I would say that It can be possible only when the demand for fiat diminishes by the common man and that will happen only when the crypto reaches everyone which has not been able to happen so far. So I doubt it would even happen in the decades to come.