Good question. I asked @steempeak / @peakd about this in the past and they indicated currently they are planning on remaining closed source.
I agree it would be ideal for work supported by the SPS to be open source. It sucks that @peakd could disappear tomorrow and the SPS-funding would have gone to waste.
Perhaps there is a model where they can make many of their features open source. I would be willing to support a second @steem.dao proposal for them to become open source.