Currency failure generally occurs due to the type of hyperinflation, and there is always the potential for technical failure, currency competition, political issues and so on. As the main basic rule, there is no currency that can be considered very safe from failure and difficult times. so is it possible that bitcoin can become worthless?
For me as long many people used bitcoin,,bitcoin will survive. I used bitcoin personally to buy load and to pay bills, so I think bitcoin will never worthless. Bitcoin now is popular in many country and have good foundation that never worthless in the future.