"I teach online advanced-Python programming workshops every month... In the last 2 months, it's consistently 60%-70% Python 3."
I teach advanced Python (and machine learning) courses too, albeit in corporate settings (groups of ~15, rather than 100), and it's still very much <20% for Python 3 there.
There's definitely going to be pockets of resistance. My attendees are a very wide-spectrum sample from many different companies and industries and even countries, so I have some faith in the trend that's showing up. Could be that there's some bias in my students for sure. Regardless, the ratio I've been seeing has been steadily increasing month after month since late last year.