Bitcoin will not fail. It is a very young currency, and many new features are being built into it that makes it better than ever. Just like the internet is the underlying technology that powers the entire internet, the blockchain is the underlying technology that powers bitcoin. Other forms of digital currency are being built on the blockchain. All of these will continue to grow and expand and become more widespread. The blockchain, unrestricted by being tied to any one digital currency, will continue to grow as well.
Bitcoin and blockchain are not the same. Bitcoin is a currency that makes use of blockchain while blockchain is the technology that powers the transaction. Anyways the both of them are new and the world is getting to know about these new technologies and how to make use of them in a way that they would benefit the world. And of course there is nothing like failure for any of these.
Blockchain on its own is very useful and is believe that it would power a lot of things in the future and not just transactions. Bitcoin too is also useful and so far it has been the truly decentralized cryptocurrency that we know.