GlobalFoundries was loud and clear that it planned to skip 10nm. But, to be fair, even Intel cannot get 10nm right. We know that companies like Qualcomm will launch 10nm products in the mobile space but it is not clear when high performance chips such as GPUs and CPUs will surface in 10nm FinFET.
Vega 10 arrives in the first half of 2017 and will get replaced by an updated version called Vega 20 by late 2017 or early 2018. However 2017 is optimistic and when it comes to GPUs it is better to expect them later rather than earlier. Fudzilla has exclusively mentioned that AMD is working on a 7nm products and one of them is codenamed Starship and should have 48 cores.
The Vega 20 with PCIe 4.0 and updated memory interconnect should get AMD through better part of 2018 while 7nm FinFET Navi is ready. AMD went public that Navi is planned for 2018 and it even suggested that it might use a next generation memory.
That could be called High Bandwidth Memory 3, but it remains to be seen. GPUs on the high end rely on chip stacking, something that we seen with HBM 1 and that we will see more in 2017 with more HBM 2 products on the market.