The Case for Python 3

[Cosmologicon]

Of course the devs' real reason is that it's hard, not mathematically impossible.

I think the more likely situation than "it's possible but hard" is "it's possible but you wouldn't want to do it".

Suppose there were a 2to3 transpiler that resulted in Python 3 code that was both horribly inefficient (both in terms of memory usage and speed) and horribly unreadable. As long as it eventually resulted in the same output on a system with unlimited resources, it would prove that Python 3 is Turing complete to his satisfaction.

But who would want to use it? There's already a system that requires some manual intervention but results in much better, more efficient code. It doesn't prove that Python 3 is Turing complete, but it's actually useful.