The upcoming 340.* legacy driver series will be the last to support the G8x, G9x, and GT2xx GPUs, and motherboard chipsets based on them. Support for new Linux kernels and X servers, as well as fixes for critical bugs, will be included in 340.* legacy releases through the end of 2019.
For more information on the support timeframes for 340.* and other legacy GPU releases, please see: http://nvidia.custhelp.com/app/answers/detail/a_id/3142
For a list of GPUs supported by 340.* and other legacy GPU releases, please see: http://www.nvidia.com/object/IO_32667.html