I think bitcoin could last until the end of the internet era, probably in a very long time.
There will be other cryptocurrencies, but there is no reason for bitcoin to stop.
Unless some people who has their dark plan plots to take bitcoin down. If what happened in Mt. Gox happened again these year, the price will dramatically go down and I think people will start to be dissapointed to these results. It may be one thing to take bitcoin down it is also the effective one.