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.
BTC has been tested and survived a long time for a new technology. Each year it seems less likely it will fail. Each day, it seems more likely it will thrive. I've never seen so much positive news about bitcoin before. It's pretty hard to imagine the world would turn on it now. Should be around a long time.