My own personal hope is that we will see cryptocurrencies develop into currencies we will use on a daily basis. in my opinion, bitcoin will be a good place to start due to the mainstream knowledge about Bitcoin, but I do not think it's the best-suited kind for daily use and I believe we have a long way to go before it is a viable alternative to Fiat currencies for the majority of people.
For inspirational purposes, I have included my article
https://cryptoms.online/2018/02/27/will-bitcoin-become-a-daliy-currency/
It's good to know that you are really optimistic about the mainstream use of Cryptocurrency. But personally I don't see cryptos being used as a currency due to its decentralized nature. We live in a strictly centralized world where, if a stock price is moved more than 10% within 15 minutes, the trade of that stock gets suspended by the stock market for half an hour. We call it circuit. I don't know about any other countries, but it happens in India.
But 10% price movement is a normal thing in Cryptocurrency market within an hour. So you can imagine the difference. Bitcoin looks good as a store of value but not as a daily currency in any way. Eventually all countries will have to adopt bitcoin but that certainly doesn't mean that it will replace fiat.