bitcoin will last forever, because there are still many people who believe to invest in bitcoin, bitcoin will die if people start not trusting bitcoin anymore and nothing else is invested in bitcoin, that's where bitcoin will die and can not survive anymore. until that does not happen, bitcoin will still survive.
Anyone can know that situation, but when that worst situation happen? No one knows it, so we do not need to care and waste much time about this case. I do not think will be disappear earlier than next 10 years.