I was lucky enough to see that article too, and it looks curious to me that @roadscape was mentioning the fact that a lot of the information that will be used by this new layer will not be stored on the blockchain but instead it will be kept on a traditional database which will e synchronized with the blockchain. From his post:

Much of the information that app developers want to leverage is not consensus-critical; that is, it either does not belong in a blockchain node or it doesn’t need to be accessed directly from one. Instead, we can store all the relevant information in a traditional database and keep it in sync with the blockchain, while adding new custom layers of logic and features.

It seems that the guys from Steemit Inc are doing this as a measurement to improve the performance and also the flexibility that they want to give to developers which is a great thing for the future of Steem and also for its scalability!