What are the chances of living in a world with no actual money ? 
Low. I think personally that cryptocurrencies wont make FIAT useless, but I think that cryptocurrencies will work hand-in-hand with FIAT money. Especially in countries like the United States, and the other first-world countries; I don't see FIAT going anywhere soon.
Exactly as I thought. Fiats are needed especially to make a quick transaction or a transaction without involving gadgets or internet which might not be available or accessible hence using digital assets would be useless and would delay the transaction. Both digital cash or cryptocurrencies and fiats need to work together hand in hand to offer a much convenient way to provide more options to do a transaction.