Live without fiat?
Obviously, for now, it's not possible as mass adoption of cryptocurrency is still in the early stage.
But as time proceeds day by day many will be thinking about accepting cryptocurrency as payment for their business and services by which will be the reason us to live without fiat and start living using cryptocurrency to get our needs.
More the question is - can we live without cash?
I think we can if we are full stock in our home, so we don't need to buy something. But it's almost impossible because if we are lived in the big city, we really need cash to buy something even if it just 1 cent. But if we can use crypto and there are many available offline stores in around us, I think we don't need to cash because we can directly use that crypto to buy whatever we want.