First of all, thanks for the survey!

After reading the notes, especially about last part on storage and bluetooth I was thinking: what if control panel provides only basic support for storage and bluetooth, but the architecture of it is such that for each applet, before to run it it checks whether an app named <applet>_extended exists, and if so it launches that app instead of the default applet.
This way Nemo can be designed providing e.g. just a basic feature for storage applet, and leave developers to design something more complete.
Also, the concept could be extended to the point that, in cases like application management where only an external app will exist, control panel could even provide a 'stub' (via a configurable option "show all stubs" ?) to launch that app, for those who still prefers to reach it via control panel.