I was under the impression that curl worked on more platforms than Rust and LLVM. It will be interesting to see what happens to curl support on those platforms going forward.
As the article indicates, it would be but one of dozens of existing backends, although it'd be one where few alternative backends currently exist (HTTP/1 and HTTP/2).
For instance libcurl can use any of 13 different TLS backends (one of which is already in Rust), or 3 different HTTP/3 backend (one of which is in rust).
Libcurl supports multiple compile-time backends for http support, encryption, and so forth. This will be no different. Hyper will be just one option among many, as will Rustls.
For instance libcurl can use any of 13 different TLS backends (one of which is already in Rust), or 3 different HTTP/3 backend (one of which is in rust).