Bitcoin disappearing in future would cause a very big damage in the world's economy and can lead to financial crises, but then I think bitcoin disappearing in future is impossible because of it's decentralized nature.It is not controlled by any one, not even the creator Satoshi Nakamoto can control it. Secondly so many financial institutions and investors have invested hugely in bitcoin and couple with it's wide spread adoption as a digital gold and store of value it cannot disappear. Though bitcoin has a limited supply and created to be scarce with time and even when the whole bitcoin is mined it will not still lead to it's disappearance instead will cause appreciation in it's value.