I said it before, but I'll repeat myself: For digital possessions, we need a clearing house. Everyone offering music, videos, etc. for sale or long-term rent, needs to register a digital copy in a standardized format with said clearing house. Every sale has to be registered there as well. Whenever the seller disables DRM or does locks out the buyer in any other way (not supporting new or old devices, closing down accounts, whatever), the clearinghouse will handout a copy to the buyer. The usage of the clearing house will be mandated by law.