Yeah we will be open sourcing it, mostly the governance/economic model will be built on parity substrate so anyone can deploy or upgrade that system. I think solving the ad driven business model is much more important than decentralizing the content servers, hard to meet the UI/UX standards most people have when you go this route also.
This is surprising to me. I didn't think that platforms that leverage network effects were typically well-suited to open sourcing unless it was something federated. Are you worried about the system being gamed or usurped by someone willing to be more exploitative?
I think proof of stake/liquidity providers with lockup creates enough incentive to keep the network effects within one system. Open sourcing the application side is a bit trickier.