Those projects were done and ran in actual hardware.
I am making the counter point regarding OP statement that Python is suitable to fully replace Java ,regardless of the implementation. Lets not mix languages and implementations.
So given that even PyPy does not match the performance of most Java implementations, it seems a bit hard to consider the scenario of Python fully replacing Java's use cases.
Sure, in Java applications where performance is critical it might be hard. Is this all Java applications? Is this even most Java applications?
I'm not necessarily agreeing with the original point that you can rewrite any Java app in Python, because that's ridiculous as well. But your counterpoint that it can only happen "when a user-space could be written in it" is very poorly chosen.
I am making the counter point regarding OP statement that Python is suitable to fully replace Java ,regardless of the implementation. Lets not mix languages and implementations.
So given that even PyPy does not match the performance of most Java implementations, it seems a bit hard to consider the scenario of Python fully replacing Java's use cases.