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.
I certainly agree to that, it is hard to predict because the future of bitcoin is still unpredictable. However, I do believe that bitcoin will have a good future and it will last for many years. In addition, I think if there is a lot of people who believe in bitcoin it will really last for many years. Lastly, I think bitcoin and all cryptocurrency will last for many years.