A leaker going by the name "USG Ishimura" published some details about NVIDIA's Volta GPUs at the Baidu forums. As usual, we recommend taking this news with a grain of salt as we don't know how trustworthy this leak is.
The news is that NVIDIA's Volta promises "really strong" performance thanks to big architectural changes. Whereas Pascal has roughly the same streaming multiprocessor (SM) configuration as its Maxwell predecessor, Volta is expected to feature a new SM architecture capable of delivering a big leap in performance-per-Watt.
Secondly, the leaker also claims there will not be two but three high-end gaming GPUs from NVIDIA. The current generation has the GP102 and GP104 GPUs for the high-end market, whereas the previous generation featured the GM204 and GM200.
The Volta generation will reportedly feature GV104, GV110 and GV102 GPUs. It is now clear how these three products will be diferentiated. The Fool report suggests the GV110 may be an even-higher product than the GV102, enabling NVIDIA to launch something even more expensive than this generation's $1,200 GeForce GTX Titan X. Personally, I don't think this is likely as it doesn't make sense to have two super-expensive GPUs for the gaming market.