it's hard to predict how long the bitcoin will last, but definitely bitcoin will survive if in the internet world still exist, because bitcoin is virtual money then bil without internet there will be no bitcoin and nobody uses bitcoin, then if any country still legalize bitcoin to transact then bitcoin will survive, because if bitcoin has been declared illegal by the government then bitcoin scope becomes limited, even disappear and this makes people leave bitcoin. Besides the factors that make bitcoin will survive is the level of popularity and the price is profitable because when both are gone then people will not be interested in bitcoin and leave it to look for other crypto currency more profitable and more popular than bitcoin