If the rumor is accurate, we may see availability of these cards in August, or perhaps even in July.
As far as we know there will be a private press event at E3, but we should not expect card announcements there. What is being brought as a potential date for new cards is, in fact, Gamescom in August.It's believed NVIDIA will introduce one card faster than the RTX 2070, and another one with more performance than the RTX 2080.
Other journalists, who were present at the Computex floor, have confirmed that AMD partners have no final pricing on Navi. This is because they still don’t know what the response from NVIDIA will be to RDNA architecture, but they might know more than we do.