https://boats.gitlab.io/blog/post/2018-01-25-async-i-self-re... and the two follow up posts are the latest thinking on this topic, and by latest, I mean "posted in the last few days". This is cutting-edge stuff!
The intention is for this stuff to support Tokio; that is, generators make asyc/await work, which lets you write futures code more easily, to be run with Tokio.
The lifetime binding tricks feel reminiscent of template metaprogramming-fu in C++, though the parts that have to be reasoned about past the standard library seem smaller and cleaner.
In Rust, it feels like we are leveraging our cleverness to accomplish a higher order of expression than what’s possible in other imperative languages today. In 20 years, maybe we’ll be talking about a promising new language concept that reminds of how exciting Rust lifetimes were back in 2018 :)