AMD has announced in an earnings conference call that its 7nm Navi GPU series will be launched in the third quarter of 2019. It is expected that there will be some sort of revelation about Navi at this year's Computex, which starts at the end of May, with a possible full reveal at E3 in the second week of June.
https://www.notebookcheck.net/AMD-confirms-Q3-2019-launch-for-Navi-initial-price-will-be-cheaper-than-the-Radeon-VII.419852.0.html