According to SK Hynix, its GDDR6 memory chip production should begin in 3 months and this should coincide with Nvidia's announcement of the GTX 11 series of gaming GPUs. The whole next-gen series will benefit from the GDDR6 memory, with the GTX 1180 likely to integrate as much as 16 GB GDDR6 VRAM, and the GTX 1170 models getting only 8 GB.
https://www.notebookcheck.net/Nvidia-GeForce-GTX-1170-1180-could-arrive-in-July-with-8-16-GB-GDDR6-VRAM.293586.0.html