> If the folks who work in that area are supportive
Rust has teams that make decisions to accept designs in their part of the project. They look at proposals and decide to accept, reject, or postpone them. This process can take a while, depending on all sorts of factors. Sometimes a design may be good, but it may not be the time yet, which is when postponing happens. Sometimes it's a "we don't plan on doing this" and that's when things get rejected. Even if a design is accepted, we don't require that people proposing the design do the implementation work, so if you do propose something and it does get accepted, it may take a while until it actually exists. Furthermore, stuff is in unstable at first, until people can gain experience with the feature, so even after an RFC is accepted, it takes some time until it's "stabilized," at which point it's part of the language proper.
Happy to answer any other specific questions!