There's a new posting on the NVIDIA Knowledgebase about "EOL driver support for legacy products." Beginning with the "Release 343" series (as of last week the 334.21 Linux driver is the latest available version) there is no GPU support prior to the GeForce 400 series and that's now been confirmed via this official NVIDIA.com entry.
NVIDIA is ceasing to support their older GeForce 8, 9, 200, and 300 series from their mainline driver but the NVIDIA 340.xx driver series will become a long-term legacy driver that they will commit to supporting until April of 2016. This is good considering NVIDIA takes good care of their legacy drivers and they still ship new releases with bug-fixes and new X.Org Server / Linux kernel releases for even older GeForce GPUs. NVIDIA takes their legacy drivers much more seriously than the AMD Catalyst Linux Legacy Driver that rarely sees new driver updates, but on the other side of the table, AMD takes good care of their open-source Linux graphics driver.
This announcement will leave some NVIDIA Linux customers disappointed that no further optimizations or new features will arrive for their pre-Fermi hardware, but it makes sense given that Fermi is already four years old and the 334 release stream introduced Maxwell GPU support. With another two years of legacy driver updates, that will mean the GeForce 8 series (the oldest hardware being dropped now from the mainline driver) will have seen ten years of binary driver updates. The hardware being dropped is for all Direct3D 10.0 / OpenGL 3.3 and older GPUs with Fermi being NVIDIA's first DX11 GPU and supports up to OpenGL 4.4. This end-of-life announcement for NVIDIA GPUs isn't limited to the GeForce series but also affects the older Quadro and Tesla products too.
For those users of hardware being moved off to the legacy driver, unfortunately the open-source Nouveau driver still isn't for everyone. Dynamic power management / re-clocking is still sorely missing from the Nouveau driver for delivering better power savings and also maximum performance when using this open-source NVIDIA driver. Other features like SLI and advanced AA modes aren't found with this open-source driver and it also tends to be frequently prone to regressions.
Those curious how NVIDIA's performance has evolved going back to the GeForce 6 series, last month I did a major comparison of GPU performance and power efficiency with hardware spanning from the GeForce 6600GT through the GeForce 750 series, plus there's our hundreds of other Linux graphics card reviews and Linux GPU driver articles if you're now thinking about upgrading your hardware due to this announcement by NVIDIA.
On the AMD side, it was in 2012 that they dropped Radeon HD 2000/3000/4000 series support and for Linux users that effectively meant shoving them over to the open-source Radeon R600 Gallium3D-based driver due to their legacy driver for this hardware being seldom updated. The latest Catalyst 14.x Linux driver releases still support the Radeon HD 5000 series and newer.