This problem is (so far) solved by the editions feature. Breaking changes can be made to the language without splitting the ecosystem (like python 2 vs 3).

https://doc.rust-lang.org/edition-guide/editions/index.html

Rust has a 6 week release cycle and a big complaint is that the language isn’t changing quickly enough so there is pushback from both ends to take into account here. My take is that there are only hard problems still to be solved given that that they need to be solved in a zero cost way.