The eventual closing of the MSN Music store sheds light on one of the biggest potential problems facing the DRM-ing of digitally distributed music:
When the store closes, when the publisher dies or when it is no longer economically feasible to continue support for these DRM schemes, all of the people who bought and paid for that music (or rather the rights to listen to that music) are going to be up the creek without a paddle. Some future MS operating system will no longer support the files, they won’t be able to copy them to the devices they want or they may even be rendered unplayable.
Historically, the solution to this would be what people have been doing with out-of-print computer games for years- building communities, emulators and the like around the joy of using this old tech. Unfortunately for us, when it comes to unlocking your old MSN Music files, or your old Protected AAC, you will be breaking the law.
What then are your options? Of course people will likely break the encryption anyway, as they already have. But the fact remains that unless the laws are changed they will not be able to legally access music that they paid for due to nothing less than the inevitability of progress.