Note that these forums are primarily for user-to-user communication, and that NVIDIA never comments publicly of future product plans as far as I have observed. However, again based on observation, when NVIDIA marks a feature deprecated, they will remove it eventually, although removal has at times happened only several years after deprecation.
The following is all speculation on my part. For an authoritative answer, you might want to contact NVIDIA directly.
From observation, the vast majority of CUDA programmers appears to use the runtime API. A relatively small number of CUDA programmers use OpenGL interop. That leaves a tiny number of CUDA programmers who use OpenGL interop with the driver API. Maintaining dual APIs means additional work, and that extra effort may not be warranted for the small number of OpenGL+Driver API users. There may also be technical aspects, in that the runtime API can easily carry a lot of information under the hood.
I would think that for as long as NVIDIA supports OpenGL, there will also be support for OpenGL interop in CUDA. That is needed for professional CUDA-accelerated visualization products, in science and elsewhere. But the information you presented above leads me to believe that OpenGL interop with the CUDA driver API may be on the way out.