That is the main goal of any currency which has the backing of the government and the moment that cannot be guaranteed, the essential objective of the entire thing has been defeated. Making this statement is just to send a message to every crypto enthusiasts not be over joyed and thinking since the government is going digital, its creating room for cryptos like bitcoin and other independent cryptos but know this, its still our Yen that is changing form and every control currently present now, is very much available if not more than because with cash, some money can be lost in transit don't expect that in this new dispensation.