AMD is really becoming a "tale of two companies." On one hand, they've executed on their Zen/Ryzen roadmap like clockwork since 2017, and they were touting their performance/watt efficiency advantage over Intel at CES.
On the other, their GPU releases look NOTHING like that chart: They never released a "14nm+" (probably TSMC 12nm) Vega GPU, but they DID release a 12nm Polaris GPU (not on the chart) and a 7nm Vega GPU (the Radeon VII and the Instinct that it's based on, also not on that chart). We'll see what Navi brings, but given that there basically no rumors on Radeon VII, I wonder how accurate the Navi rumors are. It's been a very, very long time since anyone's released a GPU that targeted the middle before going for the high end.
If I had to make a bet, I'd guess that Navi is 7nm Vega with a GDDR memory controller to keep prices down. AMD has tons of experience mixing and matching GPU features with its semi-custom business (Kaby Lake-G's Radeon, for example), so it seems like something they could do without too much effort. They MIGHT add ASICs for raytracing as Nvidia did, or they might not.
That means the 2020 release would be a new (post-GCN) architecture that would probably start at the high end before working its way down (just as we've traditionally seen from Nvidia and AMD).