That's not how it normally works with those kinds of re-implementations.
Heck, Python 3 hasn't even replaced Python 2 -- and people will dump PHP for Hack? A language which doesn't even have a community at the moment, it's 99% Facebook people.
Python 3 is a different story! As you mention below outliers, let's not use them, please! GNU/Linux OS does not depend on PHP like it depends on Python.
Heck, Python 3 hasn't even replaced Python 2 -- and people will dump PHP for Hack? A language which doesn't even have a community at the moment, it's 99% Facebook people.