To expand on Steve's point, code written in 1.0 style should continue to work indefinitely, modulo soundness fixes, lints and plain old bugs. You should only n

To expand on Steve's point, code written in 1.0 style should continue to work indefinitely, modulo soundness fixes, lints and plain old bugs. You should only need to update at your own pace or because your dependencies force you to, and they shouldn't do so often if they care about supporting as many users as possible. Big changes, like async/await sugar or impl Trait or the ? operator are uncommon and they either make your code that much nicer to read or allow new constructs that were previously impossible.