Nothing in this world will last forever...Years ago there was no paper money..People used to trade with the barter system where goods were exchanged for other goods without the use of paper money...There were also times where people used cowries as currencies..My point is,the world keeps moving forward..Day in and day out new innovations and tech pop up..i see BTC more advanced in 50 years time..If you are very familiar with the BIBLE,you realize it talks about the whole world using one currency..BTC has come to stay.