Right, I'm not saying that Apple should be Nvidia exclusive. I want both available. I think they should offer an NVidia solution as well as the AMD one. The Blender news makes it seem as if they will not be doing so. And that's a bummer!
I don't think the Blender news means anything regarding NVidia. Apple has an interest in getting things supporting OpenCL, especially if the Macbook Pro drops NVidia as rumored. It may be Apple wants apps to perform just as well if the user choses an NVidia or AMD card. They don't want to be held hostage to supplying an NVidia option on every single machine they make.
If the Mac Pro only ships with AMD for the high end, or perhaps only ships with AMD for the low end, they don't want to be stuck.