Sure, I conflated 'still compiles' with 'still the right pattern'. Its sorta like Javascript, ECMAscript has been backwards compatible but the ecosystem is a consistently moving target that users have to adopt their code to or feel left behind. E.g crossbeam and parkinglot. Also the bunch of nightly features that disappear but many use.
Sure the mainline stays clean but thats not what matters in practice.
You stated that "Rust is merging random syntaxes and random packages get upgraded to std lib all the time" as though it were incompatible with "being able to go to a program from 8 years ago and run it with no problems". But there's no incompatibility here. Rust adds new features at a faster rate than Go does, but it also maintains backwards compatibility ("stability without stagnation").