I was on the "Python 3000" mailing list while it was being planned, and the prevailing attitude seemed to be "it'll probably take 5 years before the community moves to Python 3". (That's paraphrased and not a direct quote, though I saw people say that sort of thing almost word for word a few times.)
This was optimistic, but at least we see that the community is indeed gradually moving to Python 3, even if it's taking a few more years.
Technically the goal was a majority of new projects started using Python 3 in 5 years. Regardless, everyone knew it would take several years to reach a point like this.
I switched from Perl to Python at version 3.4, and while it might be popular for people already invested in Python 2 to downplay the syntactic improvements, they were a big deal in convincing me to switch to Python as my go-to infrastructure language.
This is true, but currently, most of developers of Python acknowledge some mistakes in the Python 3 transition. Specifically the fact that such an abrupt compatibility break was underestimated. And that's why Python 4 won't break compatibility with Python 3.
In any case, I'm very happy to see the Python 3 transition moving forward. And let's hope this does not happen again.
This was optimistic, but at least we see that the community is indeed gradually moving to Python 3, even if it's taking a few more years.