I am a proponent of LTS for Python 2.7x and existing libraries. This walrus operator is a fine new feature, for those that want it in Python 3.8x and beyond. Sorry, not sorry !
I hope that 2019 is the year of PyPy adoption, as folks get ready to leave CPython.
[0] https://morepypy.blogspot.com/2016/08/pypy-gets-funding-from...