[mixmastamyk]

Looks like a lot of the guide assumes you want to run on Py2 and 3 concurrently. The time for that has passed to be honest. A clean port is easier to do.

[zdw]

For larger code bases making direct jump straight to Py3 that breaks Py2 compatibility without a transitional period can be problematic especially if it's a library.

The time may have passed, but lots of code is still out there that needs to be updated.

[mixmastamyk]

Maintaining two branches shouldn’t be a problem. If you waited this long to port, velocity on the legacy branch can’t be especially high.

Now that I think of it the legacy branch should be eol soon.