Looks like Mac is missing from the announcements, wonder what happened there then!
It looks like it will be Nvidia only, as the system requirements only mention Nvidia. You will need a 1GB NVIDIA 640 with the 364.19 driver at a minimum.
Very exciting, our first proper F1 game will be on Linux May 26th. I will be ignoring all the reviews and taking it as I see it, as the reviews aren't amazing.
Looks like it was this previous clue which has now vanished.