Hi Martin,
... but in the long run, starting now will have saved you a lot of pressure in the long run, and stop users from switching away from your packages because of lack of Python 3 support.
In a production situation it works the other way around. If there's an application that requires twisted (or whatever package) then most people would use the appropriate interpreter to match the library.
Since you guys all did your jobs so well :-) doing so is painless.
Because there is so much "comfort" with the existing situation it makes it an effort for people to move to a different lounge chair. Namely python 3.
I'd suggest that moving the package set (pypi) to python 3 could be kicked along with the help of some automated tools. I don't know what tools you guys have got.
But I am very sure that if code analysis was provided to package developers on python 3 (so they don't have to run it themselves), then it would be like an even bigger tv screen in a bigger lounge room and it would assist in drawing them over.
David