"If we ship Python inside of Firefox, no one is going to use it because it's not available in Chrome, it's not available in Internet Explorer." Oh yeah? Try me.
It's true though that getting even two major browser vendors to agree on supporting another scripting language in addition to JS, is really really hard. I don't see it happening unless Nadella's "Really Good, Honest! (TM)" Microsoft makes some sort of grand gesture towards Google or (more likely) Mozilla.
Python is also only just starting to explore optional typing which is obviously a prime feature of Dart and JS derivatives like TypeScript.
Heck, there are existing python minification tools.
- Let there be pojs landing page
- Download pypy.js in the background
- Run python code
- Dance with Glee!