It also was in a minor version change 1.8 -> 1.9, but people moved on because 1.8 was declared EOL this is what Python was missing. Python 3 is 10 years old and 2.7 is still supported (bufixes, but still).

If you look at timing, Python 3 picked up for new projects in 2015, when PSF declared that no new features will be backported to Python 2 from 3.

I believe the industry will wait for 2020 to start migrating existing code after Python 2.7 will be declared EOL.