How does one spin up a mirror of the entire WordPress.org registry, not to mention keeping up with plugin/theme updates that are uploaded there by the respective maintainers?
Furthermore, does WordPress even support custom resource registries?
Furthermore, does WordPress even support custom resource registries?
https://plugins.svn.wordpress.org/
If so, I'd imagine creating a mirror of the registry would start there.
Does Matt really want to risk creating alternative repositories and losing the central role wp.org is providing (yes, free of charge)? What about plugin authors who want to ensure their stuff is available on all WordPress hosts, what will they have to do to push to all stores? WPEngine acquired some pretty popular plugins (acf, deliciousbrains), it'd be a shame to see them exclusively available outside of the wordpress.org ecosystem as a retaliation.
Don't worry, though, Matt has generously given them 72 whole hours to figure out exactly how to do it, and complete the whole mirroring process, too! Oh, he did that on a Friday afternoon, just before the weekend? Extra generous!