Bitcoin is so popular for now because of its price value which is based on the real money or the so called fiat. If you say that real money will be replaced by bitcoin, then bitcoin will have its fixed value on your hand. If you have 10 BTC in your hand, then it will be always be 10 BTC but its value is deppreciating just like what the real money has now, which is the value is based by the foreign exchange. It will be only converted to other cryptocurecies to be used. Just like dollar into euros and vise versa. What is the point on that? Why change the current cash into cryptocurrency?