Mantle might already be history according to AMD

"AMD has definitely made an impact with their API called Mantle, This low level API has not only brought performance but it has also pushed Microsoft into developing DX12 which will come with Windows 10. If the rumors are true DX12 will bring around 50-70k draw calls per frame, which is around 5-7x more than what DX11 provided. But where does this leave Mantle? EA’s DICE has adjusted their Frostbite 3.0 engine to compliment Mantle and Crytek has announced that they will do the same, however DX12 is looking very promising and the question about Mantle’s future is still floating in the air."