Too early to tell.
The worst case scenario is that Blender will keep relying on openGL and OpenCL and that Apple does not update it (currently it seems OpenGL does not get an update). Thats means Blender will work on Macos but won’t take as much advantage of the GPU. That applies for mac users with AMD GPUs and not for people like me that have NVIDIA cards because CUDA runtime is not developed by Apple , but by NVIDIA itself.
The best scenario is that Blender moves to Metal, which means it will take full advantage of the GPUs.
A third scenario is that Blender does not move to Metal, stick with OpenGL but some third party come and build OpenGL on top of Metal. Its the least possible scenario but its not impossible.
- Since Metal is part of OS X El Capitan, does this mean that–in order to possibly take advantage of this technology–a version of Blender would have to be built ONLY for OS X 10.11 (which, in turn would mean that only users with the megabucks to buy a new mac would be able to run it)?
You confuse OS version with hardware. MacOS can run also on very old hardware, for example I run Yosemite on my 7 year old iMac. No I don’t think you will need a very recent Mac to be able to run 10.11 and Metal but that is not yet announced AFAIK. 3 year old macs should be fine.
Given that an open letter was written to Apple by the LuxRender and endorsed by Ton ( http://www.blendernation.com/2015/05…r-to-tim-cook/ ) was published regarding Apple’s graphics drivers, what could we blenderheads on macs expect in terms of new versions of Blender being released in the future at this juncture? Or is it too early to say?
Not much, Blender is a very small, tiny fish and since its free its almost insignificant for Apple. Also it does not help that Autodesk, Foundry and most likely other 3d apps companies , including big game companies have already embraced Metal even before it was release on Mac. Another reason to believe that Blender may be completely ignored by Apple is that reports from devs that have access to 10.11 state that OpenGL is still stuck to version 4.1 which means that OpenCL is more less in the same position.
Blender is one of the first five open-source software packages I install on any and every computer I buy. Should I even look at a Mac in, say, two or three years from now or purchase an Asus and install Fedora/Mint/[insert Linux distro here] because Blender won’t be available for OS X?
It depends, OpenGL is not so much of an issue on Blender because it does not take full advtantage of it. Most of Blender relies on far older versions of OpenGL. The situation may change a bit with the new Viewport project but even in that case I suspect that Blender could easily compromise with OpenGL 4.1 for several years. OpenCL is the real problem here because most GPUs that Apple provides are AMD and Cycles need it. You could move around this problem getting a mac with an nvidia like I did , in that case you dont rely on Apple for CUDA since Nvidia provides it and Blender works fine.
Basically, is Metal a step forward or backward for Blender development?
Depends on how you see but I would say definitely a step forward because will give access to far more GPU acceleration for Blender but that also means more work for Blender developers.
Blender is one of the first five open-source software packages I install on any and every computer I buy. Should I even look at a Mac in, say, two or three years from now or purchase an Asus and install Fedora/Mint/[insert Linux distro here] because Blender won’t be available for OS X?
Most likely yes, I think Blender will eventually move to Metal. The problem is what happens in the meantime, and I suspect Blender devs will wait and see how Metal works out for Apple . But I yeah I find hard to believe that Blender wont take advantage of Metal at least partly if its so much faster to opengl.
For example Blender may keep using OpenGL on Macos and use Metal only for Cycles. That could work well so they wont have to maintain both CUDA and OpenCL.
I think what we see here is a situation similar to Cycles when the main dev left, its easy to panic, but the best way is to wait and see. In the end practical minds will come up with practical solutions.