nothing lasts forever this is the most obvious thing, things change every time but if btc would be able the change itself than it will last for a long time at least until our generations die which is forever for me.
You are right nothing survives long enough but the bitcoin technology is integrated in such s way that it is going to stay for a long duration of time.and with the competition of altcoins this technology has increased his life span. Its is going to grow further and further as soon as people starts knowing about the technology. Its still unknown to many people of the world living in rural areas.