Blockchain is going to change the world, and connect everybody, but the underlying protocols (i.e. Bitcoin, Ethereum, etc) are the utilities that will foster a Free society.
Bitcoin uses the blockchain to decentralize the monetary system. With Bitcoin, the world becomes the Decentral Bank. Bitcoin also allows data payloads to be sent in txs; hello, Memo :)
Blockchain doesn't really "decentralize society". All it does it take a central database and spread it over a network with a set of rules to which all participants agree - consensus
blockchain is the best database system for decentralized networks of participants. Centralized databases are best for centralized entities (think small/med business w/ database server)