Agreed--there needs to be discussion and thought about how this impacts library maintainers. How do they tell users their library supports or doesn't support non-GIL mode? Will pypi have new metadata to specify and enforce and projects dependencies support non-GIL mode, or is just a chaotic free for all where users have to figure that out themselves? How will a library author have one codebase that supports both GIL and non-GIL mode--will they effectively fork the code and maintain two codebases (yuck!) or will there be support for detecting GIL mode? How does this work for C extensions too? There's a ton of work to make this smooth for libraries and I really hope it is being thought through better than the python 2 to 3 story for library authors (which was no story and chaos).