But we're not talking about some optional feature you can just shim in 1kb of JavaScript, we're talking about the language used to write a web app. Sure, you could use PyPy.js as a fallback, but you'd essentially create a horrible loading experience for >99.99% of your users while you wait for this addon to catch on (which won't happen, because there's no reason for an end-user to install it). For a language like Python to be natively supported on the web, at least one major browser has to support it. And that's not likely to happen given the current state of affairs.
