AMD has released the WHQL version of the Catalyst successor, the Crimson graphics driver. Crimson 15.12 is the certified version of the Crimson Edition 15.11.1 (beta version). The release notes are available HERE.
Crimson 15.12 Desktop Downloads
Crimson 15.12 Notebook Downloads
Crimson 15.12 is an OpenGL 4.5 driver and exposes the same OpenGL extensions (308 for a Radeon R9 290X) than Catalyst 15.7.