I don't work in this area and may be naive, but I would think if OpenGL adopts some of the same methods as Mantle resulting in there being < 5% performance difference between the two the business case for maintaining Mantle will go away.What I'm questioning is the slide and claim that in the future we should continue to develop some portable version of Mantle alongside DirectX/GL - that simply doesn't makes sense in my opinion unless there's an absolute failure to integrate the relevant improvements into those.
Let me put this another way... what's AMD/DICE's move if NVIDIA (again, for example) says "sure, let's standardize the Mantle concepts but we'd like Microsoft onboard" and the result becomes a new DX version (or similar for some OpenGL reboot)? Does AMD continue to develop new versions of Mantle along-side that effort? If truly the goal is to get to a portable, standard API, that should be considered the ideal end-goal for everyone, right?