The InterPlanetary File System gave us distributed block storage and peer-to-peer primitives. The impact was strong and lasting, but the problem was mutability: how can we build dynamic applications that scale on this exciting new medium?
No Blockchain Required
Using CRDTs, a novel data structure for replication and consensus, OrbitDB achieves strong eventual consistency across a peer-to-peer network. It's not a blockchain, but it can handle myriad use cases. Check out all the projects, including decentralized Netflix, Spotify, and Dropbox at awesome-orbitdb.