BTC,ETH and XRP might become a little bit more popular after 4 years,but they will definitely never be in the mainstream.More people will know about the coins,but the amount of real active users won't increase with more than 25-35% due to the price volatility,regulatory chaos and the crypto hacks/scams.
Yes, as long as cryptocurrencies possess such qualities, real use will be unlikely. Cryptocurrencies are used as investments, secured only by the expectations of the future.
The value of fiat money is regulated for reduces volatility.