I think it is impossible to replace with conventional money, even the government alone is not possible to allow it.
the government of Japan allow to use bitcoin so if they find the benefit of it then they will announce to use only bitcoin for the state which can happen in other countries too. They will then love bitcoin and will allow their citizens to use bitcoin only and they will support this currency.
Some business in Japan like to get in with the trends and they are trying to use Digital technology to pay for things online and offline. If people would want to purchase something without a wallet then they could just scan something in order to receive whatever it is that they want. Bitcoin will advance the progress of that technology.