Well something what to expect of that navi presentation would be looking in the past what amd said about their last major new GCN mach update Vega at the Hotchips 2017. And at the that time Vega had been out since FE edition launch, though RX Vegas were launched just a few days before that presentation.Hot Chips is not where you go to launch a consumer product like Ryzen or Radeon, it's an industry conference for technical deep-dives and architectural explanations with a high to extreme level of detail. It's not consumer oriented whatsoever.
Besides, the topics of the Hot Chips talks are confirmed by AMD and Hot Chips. Zen 2 is one, Navi is another, with a third keynote for ecosystem/HPC/compute more generally.
In all likelihood:
Ryzen 3000 will launch at Computex.
Navi will be teased at Computex and launch at E3.
AMD has confirmed keynotes at both, and the timing makes sense. They might not be hard launches, but they'll be launches. The level of inventory currently doesn't matter much - it'll mostly sell out in the coming months anyhow, and AMD is always good at discounting previous-gen products.