Don't worry. The Rust community is sensitive to the desire to only install Rust with a package manager. There was even talk (a few days ago) of making an LTS version of the Rust compiler for use in more conservative distros that don't want to update it every 6 weeks.

On another front, Rust is working hard to get people off of nightly. This project, for example, uses 3 unstable features. Clippy can already work on stable (edit: code that is linted with Clippy can also build on stable in some setups), Custom Derive will be stable in less than a month, and inclusive ranges is a pretty minor feature.

I would expect this project to begin working on stable for Rust 1.15, but I'm not affiliated with it directly, that's just my guess.