I'm going to predict that.
Source 2.0 will be opengl only. It will be cross platform on windows, linux, osx. It will also of course work on next gen hardware since it's only really a PC in a smaller box.
It will be free to developers or at least a small fee if you're title is steamworks only.
They will charge a larger amount if you want it to be non steamworks.
In two years time we will have gubuntu. Gamers ubuntu, yea bitch i'm trademarking that name. It will be what's used on the steambox.
So dx11.1 being w8 only is nothing new. Considering dx11 didn't work on XP, although it is only a small increase so no one is really going to give a rats ass about .1 in the DX scheme of things.
E3 next year is going to be amazing.