Well, value, to answer the first question can be very subjective. Decentralization, the core principle and action of blockchains, if the elements of the blockchain are built and deployed correctly, can provide higher security, greater redundancy, more transparency, greater accountability and make it harder to change data without it being discovered. If those items are actually met, are they valuable? I would say yes.
Having blocks being witnessed and signed by servers potentially all over the world make it more difficult to hack, to corrupt, to lose, and to change data, while making it impossible to sensor. Once transactions are deemed valid, they are on the blockchain for as long as the blockchain exists.
Now, I suppose the technology in of itself, it could be said, is only as valuable as what goes on it. If nothing goes on it, or if it's filled up with things no one wants or cares about, does the blockchain still have value? Maybe, but there might need to be a change in what's stored there in the future in order for anyone to recognize it.