There's a bit more news / a rumour about high end Navi cards in 2020 here:
http://www.redgamingtech.com/navi-20-series-is-known-internally-as-the-nvidia-killer-exclusive/
The GPU codenames are Navi 21 and Navi 23 according to the source.
http://www.redgamingtech.com/navi-20-series-is-known-internally-as-the-nvidia-killer-exclusive/
The GPU codenames are Navi 21 and Navi 23 according to the source.