I'm not sure. All the browser APIs will still use the JS object model. If we look at the situation on the JVM or CLR, it seems like languages specifically desig

I'm not sure. All the browser APIs will still use the JS object model. If we look at the situation on the JVM or CLR, it seems like languages specifically designed for those object models (even if adapted from other languages) have been more successful than attempts to directly port existing languages. e.g., Scala, Clojure, F# or Powershell vs. Jython, JRuby, C++/CLI or IronPython. My bet would be that languages specifically designed for the JS ecosystem (whether JS itself or something like CoffeeScript or TypeScript) will continue to be the most popular for writing most of an app, with some apps dropping down to C or C++ or Rust compiled to wasm for a subset of performance-critical code.