Though nothing on earth last forever. Still yet we can't still say that bitcoin won't last forever because we haven't still yet still see what bitcoin really have for this digital world century. But I must still say that, bitcoin might not last 3 decades more.
in a currency revolution nothing can last forever, for example gold is replaced by paper currency, and paper currency is replaced by digital currencies and this kind of thing becomes a cycle, so bitcoin will last long before there is a new type of currency that can replace it .