The 2nd generation High Bandwidth Memory (HBM 2.0) for high-end GPUs might happen in very late Q4 2016 but realistically it probably won't ship until 2017 in any volume.
The first card that we expect supporting this feature might be the Greenland, a card that AMD might end up calling Vega. Even according Radeon Technology Group's official GPU roadmap, Vega / Greenland now look like a 2017 product, or at very best, late 2016 card. Nvidia might make the HBM 2.0 version of the Titan card, but we don’t expect to see a Geforce GTX based on Pascal GPU and HBM 2.0 coming to the market this year.
We managed to talk to some of the memory manufactures and they told us that HBM 2.0 is very limited in supply, and limited supply makes things expensive.
It seems that GPUs of 2016, including the new AMD Polaris and the new Geforce, will be stuck with GDDR5 and in best case scenario with GDDR5X from Micron. The word on the street is that both Geforce GTX based on Pascal and AMD/RTG's Polaris 10 / Ellesmere and Polaris 11 / Baffin might launch at Computex during last days of May or early June 2016.