It has a big probability that Bitcoin become something really big, but for sure there will ever be some fiat money, maybe back to gold or silver system to prevent a too massive inflation, but it will never die.
The bitcoin is bigger than all the rest digital coins added up. It is still being developed, it will not die soon. If it does die, that is because the community cannot reach consensus on many issues. It will be killed by its users and developers. I hope bitcoin 2.0 will replace it if it dies eventually.