My bet is that DIRECTV is working on an online app to manage the recordings. The DVRs are already streaming the playlist titles (confirmed by checking out various media players that can see DLNA-compatible devices), playlists can already be combined with Whole-Home DVR service, and Whole-Home compatible non-DVRs can be used to schedule recordings on connected DVRs. You can also already remotely schedule recordings from DIRECTV's online guide or from a smart-phone DIRECTV application.
My guess is one of the next new features to appear will be the ability to schedule a recording from one Whole-Home-connected-DVR to any other Whole-Home-connected-DVR, as most of the pieces are there already. Then it's not much more of a leap for Internet-connected DVRs to send the scheduled recordings list, the Series Link list and Playlists back to DIRECTV for access via an online tool. Combine this with the recent news that DIRCTV was surveying customers about their interest in a "Sling/DIRECTV-2-Go"-type of service (for remotely viewing recordings from the home DVR) and I think DIRECTV has got to be gearing up for an expansion of the online tools for managing DVRs...