Vulkan is basically OpenGL 2.0 with Mantle features (reduces the load on the CPU a lot for Radeon users), and games are already implementing it. Rockstar Games confirmed that it would be used in GTA V https://twitter.com/amd_roy/status/583702029488402432.
Vulkan is planned to play a big part in future games (especially in Linux), so it would be a wise move to set this to your priority list (not necessarily highest).