Yes, I also think that keeping the bitcoins for a long period is very profitable. But all the same, the currency can not replace the currency. Crypto currency will always remain an alternative currency
Well... there is a very small chance that Bitcoin may replace some smaller currency, such as the São Tomé and Príncipe Dobra or the Comorian Franc. But I am very much sure that it is not going to replace the United States Dollar. The USD is the reserve currency of the world, and it is the currency of the international trade. It will be impossible for the BTC to replace the US Dollar.