That article is more "let's describe HKTs in Rust-y terms, so that more Rustaceans understand their purpose" than an actual proposal for implementing them in Rust. Any concrete proposal (i.e. covering implementation details and corner cases, rather than just some syntax/use-cases) would need to go through the RFC process: https://github.com/rust-lang/rfcs/blob/master/active/0001-rf...
((Unfortunately?) I imagine such an RFC would spend a month or two (or more) being discussed/thought-about.... And double that discussing syntax. ;P )