AMD has decided to stop supporting all graphics cards not based on Graphics Core Next architecture.
AMD Radeon HD 8000 Series (HD 8400 and below), Radeon HD 7000 Series (HD 7600 and below), Radeon HD 6000 Series, and Radeon HD 5000 Series Graphics cards are now officially considered legacy products and will no longer receive software and driver updates.
The Radeon HD 7000 series launched in 2012 and the Radeon HD 8000 series launched in 2013.
AMD believes that this decision would enable it to dedicate valuable engineering resources to developing new features and enhancements for graphics products based on the GCN Architecture.
The AMD Catalyst 15.7.1 WHQL-certified driver will continue to be available for users running Windows 10, Windows 8.1, and Windows 7. Users running Windows Vista and older Microsoft operating systems can use the AMD Catalyst 13.12 driver. AMD is also providing a final "As Is" Beta driver together with the release of the AMD Radeon Software Crimson Edition. The AMD Radeon Software Crimson Edition Beta driver includes the redesigned user interface as well as some enhanced features.
For what it's worth, AMD insists that the graphics cards affected by this decision "have reached peak performance optimization as of November 24th, 2015."