Perhaps a good follow-on thread would be new things that have solved multiple other things that use to be hard or impossible. For example, Rust comes to mind a

Perhaps a good follow-on thread would be new things that have solved multiple other things that use to be hard or impossible. For example, Rust comes to mind as something that has improved error messages, elimination of most memory-related bugs and "fearless concurrency." All while being fast and having support for cross compilation.