It has finally been confirmed that NVIDIA will be launching a new graphics card, which will be the GeForce GTX 950, not the GTX 950 Ti. The card will be based off the GM206-250 GPU, which is likely a cut-down version of the GM206-300 processor that is used in the GTX 960.
The card will be available in two different configurations, one with 4GB of VRAM and another with 2GB. It is also likely that the card will have the 128-bit interface. So the real difference between the GTX 960 and GTX 950 will be CUDA count and clock speeds.
The card will adopt the same reference design as the GTX 960 with three DisplayPorts, HDMI and DVI connectors. We will have more information as it becomes available.