Does WebAssembly even make sense as a standalone runtime, like the JVM? Is "server-side WebAssembly" going to be "a thing", or is it just a compatibility kludge?

And what of all these languages that compile to JS, like Typescript, Reason, Kotlin, et al? Is JS a sound "IR" between the frontend and WebAssembly? Or would it be better to compile things directly to WebAssembly?

Not just for web either: if you ship WebAssembly bytecode as part of your python package, you can push your platform dependencies out to a wasm runtime and skip most of the build matrix.

A runtime like wasmer-python [0] is only 1.5MB.

[0]: https://github.com/wasmerio/wasmer-python