I love this idea. Although GitHub is not perfect, it would be so much better than a mailing list. Mailings lists are annoying: they have very poor searching capabilities, you can't unsubscribe from a thread you are not interested in, you can't follow the conversation easily because it's not always obvious what is a quote and what is not, there is this annoying rule about bottom posting that makes messages more difficult to read, there is no code formatting, no editing, no tagging or organizing of message in any way, and a lot more smaller annoyances. It's the same as SMS or any other simple chat application. It's just too limited.
But unfortunately, if it came to a vote, I would vote NO. The mailing list must remain IMHO. It's terrible and annoying but it's also very simple and ubiquitous. And that's what is needed for inclusivity. A lot of senior developers prefer this kind of communication method so if we asked them to switch over we could lose them. Not to mention people who have no access to GitHub because of sanctions. It's the ubiquitousness of email that makes it the best tool for the job even if it's actually terrible for technical discussions.
