Blockchain is a horrendously bad fit for this:
- For p2p web, look at the Onion/Tor network.
- For p2p databases, look at distributed hash tables (like google uses for their world-wide infrastructure).
IE structures that are actually distributed, not replicated.
Using a “coin miner” infrastructure to also run a DHT might be useful because the miners have to be always-on to earn money, ie they have the incentive to leave the computers on. But the blockchain data structure itself is a monstrously bad fit for … pretty much anything — and in order for miners to also/actually manage the DHT, it has to somehow be built into the incentive structure for the mining, otherwise people will just build “stripminers”, ie clients that will only mine coin but not do any of the other work.