Historically, incremental progress on the web platform has done better than attempts to take a giant sledgehammer to existing systems.
JS Competition Roadkill Gallery
- ELM (trendy, but far from common in production projects)
Is it possible that a totally new language could displace JS? Sure. Is it likely to happen soon? Probably not.
That said, sometimes good ideas from greenfield languages get merged into the standard. JS got arrow functions, destructuring, rest and spread, all of which were first implemented in CoffeeScript. In other words, those other technologies aren’t about to displace JS, but they’re still cool and useful.