I'd say it's going to be great for Linux, since usage of Nvidia will drop and progress will accelerate, because no one will have to deal with blob idiosyncrasies caused by Nvidia refusing to upstream their driver.
With Intel joining AMD on high end GPU scene with open drivers, it's Nvidia who will be the loser with their dinosaur blob approach.
As games are running both on AMD and NVIDIA GPUs, but CUDA is NVIDIA only (and supported by lots of languages and libraries), as a programmer I don't see how AMD could disrupt NVIDIA's developer friendliness/lock in (unless AMD provides a great CUDA implementation).
By great, I mean great for NVidia, not for us.