I want to try building something like this, but using Tahoe-LAFS[1] to store the packages / images, so that you could get de-duplication for free, and capability based access control. I have no idea if it would be feasible in practice yet. How hard is it to build a custom docker registry? From a glance at this code it doesn't look terribly complex to get something simple going.
IPFS would be an interesting experiment too. Mainly I want to try it with Tahoe because of two features: convergent encryption (basically a way of deduplicating encrypted blobs) and capability based security (a way of doing access control at the file/blob level, rather than role-based).
https://tahoe-lafs.org/trac/tahoe-lafs