> Doesn't it still depend on CUDA for hardware acceleration?
Assuming by hardware you mean GPU acceleration, then yes. It's not really a push for Cuda usage, most games that use physx don't use the GPU acceleration (not everyone has PhysX cards, and those that do are usually busy using the GPU for rendering), so in practice for 99% of use cases, it is open.
Modern cards commonly have rendering and compute pipelines available to be used in parallel. So in theory nothing stops games from using compute queues for physics.
So far it looks more like a way to advance CUDA usage even further, by giving a free higher level library that's locked into it.