That or potentially fast tracking merging popular libraries into the standard library. Or at least concepts from popular libraries. Basically all the "most downloaded" crates on the Crates.io front page should be candidates for merging into the standard library.
Good ideas are pulled into the standard library.
https://crates.io/crates/once_cell
https://doc.rust-lang.org/std/cell/struct.OnceCell.html
Not everything should be eligible for this treatment. Certainly not an HTTP library or something without extremely widespread applicability.
Nearly all of my projects used once_cell, so it's good to see that pulled in. I wouldn't want to see anyhow, thiserror, anything opinionated, or anything domain specific in the std. That's a weight you have to bear forever.
Remember how long Python 2 -> 3 took, and look at the ancient and awful stuff in Python 3's standard library. Rust is not the right language for this.