Shame they're going to host it on GitHub, though, rather than self-hosting. I get that the network effects of GitHub will make it easier for potential contributors to get started, but... ugh, just sucks to see a successful open source project moving to a proprietary platform for their hosting.
I'm surprised they didn't go with a self-hosted GitLab instance. I've always found GL to be better at handling large projects (projects, groups, sub-groups etc.), not to mention they could easily modify their instance to better integrate with the rest of their services.
They don’t seem to plan to use any of the GitHub features. They only use it as a “cloud git hosting”. My guess is if there was as reliable git-web hosting they might as well go with it. By only using GH for repo hosting they’re not locking in themselves and also outsource the tedious parts (infra, backups, etc.).
Too bad they're going Github, indeed. Keeping away those users that won't be willing (or able) to contribute to the project unless it's hosted on GitHub is something desirable, in my opinion.
