Blockstack project originally ran on namecoin. But it is not a secure blockchain.
Also, it stores much data in the blockchain, so it has scaling problems. Blockstack stores the zone file data in its own Atlas (DHT-inspired) network, and the zone files point to where the actual application-level data is stored.
Blockstack can work on top of any blockchain, so if Bitcoin is not the most secure anymore, it could be moved. Separating into different layers allows scaling and resiliency. And you don't have to run a blockchain, which is good, because that already exists.
Also, it stores much data in the blockchain, so it has scaling problems. Blockstack stores the zone file data in its own Atlas (DHT-inspired) network, and the zone files point to where the actual application-level data is stored.
Blockstack can work on top of any blockchain, so if Bitcoin is not the most secure anymore, it could be moved. Separating into different layers allows scaling and resiliency. And you don't have to run a blockchain, which is good, because that already exists.