I would say a p2p storage market + a DAO governed treasury.
Decentralized storage is already technically viable, as demonstrated by Filecoin, Sia, and other erasure-coding-based schemes. The key question is: What should the economic model of the storage market look like? How should storage borrowers pay providers? Is a “storage coin” necessary for transactions? I believe stablecoins and (micro)payment channels like Fiber are better fits than mandating specific “storage coins.” and on-chain payments.
Such a p2p storage market could use peer-to-peer messaging for demand/supply matching, erasure coding for data redundancy, and stablecoin in Fiber channels for payments. Storage users can broadcast demand quotes to find matches, set up Fiber payments once deals are made, upload data to selected providers, and make stablecoin micropayments through Fiber channels when retrieving data. Providers can broadcast supply quotes, accept uploads after setting up Fiber payments, pull funds once uploads are complete, etc.
If such a p2p storage market exists, it can serve as the decentralized data availability layer for Nervos, allowing apps to become more decentralized by using it. It complements CKB by storing “dumb data” rather than programmable “smart data”(stored in CKB cells). It could also be used to store “public goods” dumb data such as historical blocks and transactions (including witnesses). Finally, the costs of maintaining this “public goods” data can be funded by the CKB treasury, ensuring its long-term availability.
For now, I think CKBFS is awesome and usable. As the ecosystem grows, more options will likely emerge, and some people might still prefer witnesses (perhaps because they are DA redundant by then :-)).