According to the Zune Marketplace FAQ, Zune will close its virtual doors when Microsoft officially transitions from Microsoft Points to real-world currencies, which could be as soon as Thursday, August 22nd. Once the conversion begins, Zune users will no longer be able to make purchases or rentals from its marketplace. The application will still be usable and will continue to stream music and play content from the user’s personal media collection.
As a replacement, users are advised to switch to Xbox apps. Movies and TV shows can be rented or purchased from Xbox Video on the Xbox 360 and Windows 8 PC and tablets. Music can be purchased through the Xbox Music app on Windows 8 PCs, tablets and through the marketplace on Windows Phone.
The changes will have no impact on those who have Zune Music Passes or on your ability to redeem your 10 monthly song credits.
If you have not spent your points balance prior to this change, your MS Points will be converted into an amount of real-world currency of equal or greater value.