In case you missed the announcement, here's some truly great news:
"To better serve the game development community we now offer Direct3D 11/12 implementations of the Flex solver in addition to our existing CUDA solver. This allows Flex to run across vendors on all D3D11 class GPUs. Direct3D gives great performance across a wide range of devices and supports the full Flex feature set."
Yes! FleX is now not a CUDA-only physics library! NVIDIA devs have also utilized Async Compute to make it as efficient as possible with D3D.
Check out the GDC talk.
Hopefully we'll start seeing more FleX in the upcoming AAA-titles (or maybe even indie ones?.. Who knows!)