CUDA is the only reason I have an Nvidia card, but if more projects start migrating to a more agnostic environment, I'll be really grateful. Running Nvidia in Linux isn't as much fun. Fedora and Debian can be incredibly reliable systems, but when you add an Nvidia card, I feel like I am back in Windows Vista with kernel crashes from time to time.
What AMD really needs is to have 100% feature parity with CUDA without changing a single line of code. Maybe for this to happen it needs to add hardware features or something (I see people saying that CUDA as an API is very tailored to the capabilities of nvidia GPUs), I don't know.
If AMD relies on people changing their code to make it portable, it already lost.