On August 31, Microsoft will turn off the servers that validate their “PlaysForSure” DRM system (this predates the system they use for the Zune). This means that anyone who has bought music that uses PlaysForSure will not be able to transfer it when they upgrade or replace their computer, or get a new music player.
It won’t be an instantaneous death like DIVX was, or like a subscription system, because it doesn’t phone home whenever you try to play a track. But it’ll be a lot faster than simple technological obsolescence. I can still play my old VHS tapes until my VCR breaks down (and then I could probably still get it fixed if I really wanted to), even though I don’t think I’ve seen a pre-recorded tape in a store in years.
This is also why I prefer to check Amazon’s MP3 store first, before going onto the iTunes Music Store, and then prefer DRM-free iTunes Plus to standard iTunes tracks. Given their current position, Apple isn’t likely to get rid of iTunes anytime soon, but if they ever did, I’d be in the same boat as people who purchased PlaysForSure tracks. (Though I’m hoping they’ll move the entire catalog away from DRM long before that happens.) Whereas since Amazon’s tracks are plain, ordinary MP3s, they could abandon the business tomorrow and I’d still be able to play the tracks for as long as I can find software that plays MP3s.