I saw Steam already is on Mac. So the garden is not walled as high as i thought.
But i'm sure the amount of Mac games is still tiny.
Would be nice to see something like Proton but for Mac, to improve this. But probably this would work only if Apple takes most of the cost, because Valve does not sell any Mac devices.
That's unlikely i'm afraid. Maybe Apple plans to primarily use the Toolkit to get more content for Apple Arcade.
However, on the long run i see a need to make native ARM games anyway. Windows increases support for ARM, Qualcomm wants to compete M1, and actual handhelds hopefully pave the way to replace expensive desktops with mini PCs.
That's where i see a valuable future for games. Goggles not so much, even if cheap. Also: If SoC becomes the gaming mainstream, NV surely wants ARM support as well.
With that in mind, supporting Vulkan would be much nicer than the Porting Toolkit and probably even easier to do.