Too early for this memory
Volta is out for artificial intelligence, machine learning applications and it will be shipping in DGX 1 systems, mainly for deep learning and AI. The next Geforce will be a completely separate chip.
Too expensive, limited supply
Our well-placed industry sources have told us that we should not expect to see the HBM 2.0 based GPUs shipping anytime soon. Nvidia Pascal and AMD Polaris 10 / 11 will stick with GDDR5 memory for the time being.