Crypto currency has appeared recently and is only at the beginning of the path of its development.
Provided that it can demonstrate progress as a means of exchange and a unit of account - the same as demonstrated as a means of accumulation - the crypto currency is a viable technologically new form of money.
How do I think the main problems that the crypto currency should solve:
1 Scalability. Many crypto-currencies are built on chains of blockers that are not designed for large amounts of transactions.
2 Ease of use. As with any invention, convenient design is the basis of acceptance. Crypto-currencies today require special understanding.
3 Regulation. Crypto-currencies need common rules, whereas now in each country the issues of regulation are solved in their own way and only fragmentarily.
4 Volatility (variability of the exchange rate). Fluctuations in value are inherent in all currencies, but in the case of crypto currency it is excessive.
5 Incentives. Any new financial system should answer the question of how the reward will affect its behavior. If it is not built correctly, this will allow one user to manipulate to the detriment of others.
6 Confidentiality. For users, different levels of confidentiality must be available.
As soon as these problems become solvable, immediately the crypto currency will become our present and not the future!