Sure, not interested in changing the past, for many reasons not least of which is that it appears to be impossible. The Python team surely did not go in to Python 3 blindly, but they botched it anyway.

What I mean to say is that Python as a negative example only goes so far, because an example of failure isn't a template for success. So "don't do what Python did" carries limited value for a language looking to make breaking changes. For a language looking to make a major point release, that's the future, and the future can be changed; this is what I'm interested in here.

"Do what Perl 5 did" (and do not do what Perl 6 did, up to the point it got renamed) is a great place to start, however, because it worked, works, is working. Languages are different enough that it isn't a completely transferable experience, but there's a lot to learn there.