It could still work. The fact that they're dropping it seems spiteful. It could work like this:
You pick your 10 people that you want to be in your family circle. When a circle is made, that circle will receive a unique encrypted ID number that would be downloaded to the console of each person. As long as that encrypted number matches, and that file exists on the console, those people can trade and see each other's game library. The two concurrent user limit would apply. Whoever bought the game originally would activate his/her own console 'token' and another person in the plan could request an active 'token'. To activate or deactivate the tokens, there would be a quick handshake with Xbox Live (similar to deactivating and activating computers in iTunes for access to DRM content). To clarify, this would only apply to digital purchases.
This apparently seems to be off the table for the time being, but it is something that could definitely work. Thoughts?