I'm not much into Python, just wanted to say you're right to value your users and installed base more than a language "march of progress". After all, a programming language is a means to an end. A couple years ago I learned Apple's CalDav server software would be discontinued/not developed further b/c it's based on Twisted (though that situation may have changed), a fact that turned me away from using or depending on Python alltogether when I can help it. Python 2 is also used in Blender and GIMP as a user scripting language with limited test coverage still (I believe), and a couple other highly specialized and valuable F/OSS graphic apps/plugins as well where developer resources are scarce, and forced obsolescence is the very last thing anybody needs.