Almost any other language can now compile to WebAssembly: C/C++ via Emscripten, Rust (it's already bundled), Go and even Swift. That offers a very nice transit

Almost any other language can now compile to WebAssembly: C/C++ via Emscripten, Rust (it's already bundled), Go and even Swift. That offers a very nice transition to the WebAssembly ecosystem, so you don't need to rewrite your business logic in other language (in contraposition to the JVM)