I'd be very happy if Gizmo or JRemote could play/manage local content and be selected as a DLNA renderer by other MC instances. At that point Gizmo/JRemote would be an android music player and effectively a pocket Id!
Local playback would be very exciting (whether accessing the android system audio database, or in a fenced off private storage location). If it was integrated into the existing players, you could probably leverage your Doctor Who logic for it to make the whole thing completely seamless (i.e. you select a track in Gizmo/JRemote, and if it can find a local match, it plays that, otherwise it pulls from the server, etc.). If you could then select tracks to download as well (i.e. use Gizmo/JRemote to manage local storage) that would be the icing on the cake.
It would save me a fortune in data and be a killer feature.
Being able to run Gizmo or JRemote as DLNA devices would also be huge as you could then convert any old android device into a zone, which would be mighty neat and give people lots of options for extra devices and/or system on a chip devices running android. You can mostly do it now with BubbleUpnp, but integration isn't perfect by any means.
I only use two apps on my phone for media management other than JRiver (Poweramp and Bubble UPNP); I would love to ditch both.