Did they specifically say it started two years ago? I believe they once mentioned the idea of a sequel came about due to having too many ideas for BOTW DLC. If that's true I'd assume they'd have been playing around with it for quite a while longer.
The presentation was more or less what I...
I think if we see anything it will be a cinematic trailer revealing more story/world elements and a little clip from the developers saying "coming soon." I personally think a mid-to-late 2022 release window is most likely. I've always felt 2021 was too optimistic even before covid.