Its already the case the language and ecosystem is so much in flux that code that's been written today has been made obsolete by a language feature in the latest nightly build.

This is just...not actually true, depending on what you mean by "obsolete". Rust has been stable since 2015; almost all code written for version 1.0 still compiles today.

Rust is risking of going the C++ way: have some many freatures bolted on that even as an experienced developer, you can checkout a random project on Github and discover a new language feature.

This is more subjective, but most of the current feature-stabilization work in Rust is not "bolting on" completely new functionality, but rather focused on reducing places in the language where different features are currently incompatible. This blog post is a bit old, but expresses what I mean: https://smallcultfollowing.com/babysteps/blog/2022/09/22/rust-2024-the-year-of-everywhere/