I think it would actually be (pseudo-)decentralized and you'd have to mine a blockchain node containing each domain, where its creators will have reserved at least 10% of its node pool to make sure they became billionaires if it took off.
You’re right that it would run on a block chain, but that fact would primarily exist to power some marketing. Everybody would end up interacting with it through a single centralized web site and API because it’s the only usable way to get it to work.
Plus micropayments, of course :-)