python 3 is off track
I love Python.
But it doesn't run in the browser, despite some tries.
And it doesn't run under Android, despite some tries.
Concurrency can be a problem in Python, but that's true of pretty much all languages. The spiffs of Python 3 are tangential to it being usable in a browser and under Android. So they are irrelevant for Python's future prospects.
Anyway, Python3 is simply another language than Python2. It's "easy" to translate Python2 in to various languages, including Python3. But doing so is work. Grunt work. Overhead. Friction.
Biting the hand that feeds IT
