Crypto currency will not and will never replace real money. Why? Because not every single person in this world are literate on high technological things and ideas and not every person in this world can afford to buy a computer or a smart phone and pay for internet bills. Do you think that the homeless people benefit if real money will never exist anymore? Yes they can earn a small amount of cash from begging or doing some tasks or what ever they do. If you get what I mean. 
Yeap i agree with you and would like to add. That all cryptocurrencies at the moment is like forex trading obligations and they dont have any possobility to replace real money. But can they replace companies that have obligations? I think yes. We really can never tell the future because our technology is very advance and we'll never know what it can unfold in the future. Real money is what we are using right now but just like creditcards we will never know bitcoins could be like that in the future and no need for us to bring cash or cheque anymore though it would take long time to implement but somehow that is something we'll be looking forward to.
That is right. Almost impossible to forecast that. Despite it seems possible, it will take very long years in my opinion. We may not see that in our life time.
We are changing to the world with digital technology.
Of couse, a cryptocurrency like Bitcoin is neccessary for this world while we are wanting to have a freedom currency.