If it were to be applied to sites on the internet, that would be proving ownership of an specific site's domain, and other info. Still, I believe that if at some point in the future, the blockchain would be used to power the internet, it would make it virtually unstoppable, especially if it would have massive hashrate just like Bitcoin's to secure the network.
Does it really need a huge hash to secure the network? Why not make it cost effective by removing the pow side. As far as I know nodes can verify transaction even without miners. And anything not acknowledge by majority of the nodes is not accepted to modify what is in the ledger. I would love to see a green world where heat generating miners is out of the scene.