Even if it is technically quite feasible, I would be seriously surprised if Nvidia and Intel implement Mantle if only for political reasons. However, they definitely will implement DX12 --which as far as I can tell is pretty much the same thing as Mantle except explicitly multi-vendor. If Mantle was a tap on OGL's door, DX12 is a full-on wake-up call.

Back when I worked in Windows/console games, my market demanded D3D (+ sony/nintendo's wacky custom APIs). Now I work in mobile and my customers demand GLES. GL advocates used to cry "GL has the better tech! D3D only wins because of politics! Boo!" It will be quite a turn if they switch tunes to "D3D has better tech, but GL still wins because of politics! Yay!"

DX12 API Preview vid http://channel9.msdn.com/Events/Build/2014/3-564

DX12 API Preview slides http://view.officeapps.live.com/op/view.aspx?src=http%3a%2f%...