Technically, speaking Blockchain.io is just making use of existing off-chain solutions! Really interesting as not that many exchanges are giving a decentralized payment network a chance. This kinda defeats the whole purpose of Crypto, hence I believe centralized exchanges will eventually not be trusted and unpopular, except perhaps for highly regulated Custional services like Coinbase for the rich institutional investors. Decentralized exchanges could take time to catch up, but the idea of semi-decentralized by simply integrating upcoming off-chain solutions! There should be an arm-race of centralized exchange integrating decentralized payment solutions like the Lightning