It is hard to predict with certainty, but usually if something is going to fail it is during its early years. Since Bitcoin is approaching 10 years it is probably past that hurdle. I would think it will probably be around for the next 10-20 years easily, then it may risk being supplanted by some other coin or even technology. It probably won't go away completely, just become not as relevant at some point.
Right, Its can't say anyone that bitcoin how long survive. But its true its minimum 10/20 years easily go. and it don't be out from market. It can be legal. Otherwise its used so much.
So from my opinion bitcoin will not vanish.