NVIDIA hasn't updated its three legacy drivers (the 71.xx.xx, 96.xx.xx, and 173.xx.xx series) since this past July when delivering various bug-fixes and new kernel support, they have updated two of their legacy drivers this week. The new releases are 173.14.22 and 96.43.14, which NVIDIA has tagged as legacy pre-releases, and both drivers now contain X Server 1.7 support along with an updated nvidia-installer to detect newer Debian distributions that use /usr/lib32 instead of /emul/ia32-linux as the 32-bit library path. That's it though for the official changes, but at least there's updates still coming out, considering NVIDIA's official open-source stack remains limited and obfuscated and Nouveau isn't yet ready for prime-time use.
As of right now, NVIDIA has not updated its 71.xx.xx display driver to offer new X Server compatibility nor do they have plans to provide an update.
For those using the mainline NVIDIA Linux driver that is now in the 190.xx series (with the 195.xx beta drivers on the way) there has been X Server 1.7 support for a few months already.
These updated legacy pre-release drivers can be found here and here.