I agree that those were not actually "promises" but "directions", and I apologise for that. Those directions were mainly cited in different conferences by some Rust-head-members at that time (Alex Crichton, Niko Matsakis, Ashley Williams, or even you), and during conversations I had with severals during Rust Fest or RustCon.
For example, I remember talking that with you at the Rust Fest 2017, in Zurich actually, especially about the *very early version* of Async/Await.
It is ok for the community to move on different directions than the first one, and I don't blame any of you for that.