A new parser for the CPython implementation of the Python language has been
in the works for a while, but the
announcement of a Python Enhancement Proposal (PEP) for it indicates that
we may see it fairly soon. The
intent is to add the parser, and make it the default for Python 3.9,
which is due in October.
If that plan holds, the current parser will not be going away for another
year or so after that. The change should go completely
unnoticed within the community; the benefits are mainly for the CPython core
developers in the form of easier maintenance.

Source: LWN.net – [$] A new parser for CPython