I'm glad most of the network seems to be rolling their own solutions. Plus, what I said really only applies to lazy miners. It's probably not that hard to set up a thin compatibility layer between B2 and Filecoin, but as another commenter noted, they charge about $60/TB/year.

If you wanted to really be competitive on the Filecoin market, you could probably set up a rig just like Backblaze does (they open source their designs) and achieve the approx $30/TB/year mark, which is basically half of the B2 compat layer.