The oldest rustc version I target (for a tiny project, admittedly) is over 6 years old, and it's fine. When code works it also works on the latest release. When code doesn't work I get a reasonable compile-time error message, not a mysterious segfault at runtime.

It's not easy, even in a few hundred lines I had to remove many conveniences to go that far back, but it's very legible. The compiler has my back, I'm never confused about whose fault it is.

Rust is young, but I don't expect this to be any different in 2030.