I did some simulation of the Volta GPU, that should slot as GTX 2060.
IMO we are looking at 250 mm2 die size, with 125W TDP. 2048 CUDA cores, clocked at 1.5 GHz. Performance around 1.8 times of GTX 1060(gaming performance). Overall Max TFLOPs output around 6 TFLOPs.
You are expecting too much, as i already wrote above. You don't get more perf/flops than maybe 5% in gaming. At least not from shaders alone. Just look at the hpc numbers:

DGEMM is nearly pure shader limited. It scales linearly with gflops and that's what you will see mostly in games if other stuff like front-end isn't the limiting factor. The improvements only help in special cases like FFT here. But gaming workload is much easier codewise.
Important is that volta makes this 40% more speed possible with the same power and such a successor i would expect. 1,8 times is too high and in no way possible on the same note (pretty sure just marketing like vega which uses the 3rd Finfet process by GF).
Ohh and because some people find it so important, hardware scheduling is back:

Found it on twitter from their deep dive into volta, but they didn't publish it online in detail.