The alternative to GitHub is already here. It is called self-hosting and there are many alternatives.
The Linux kernel is not hosted on GitHub and uses cgit. Others use GitLab, or Gitea and there is also Forgejo (Which Codeberg uses) that people are using and can be self hosted.
This is why now everyone is realising why "centralising everything to GitHub" [0] was a terrible idea and now GitHub has been (unsurprisingly) run into the ground.
The author's premise is that these all follow similar models to github and that's the problem they're calling out.
If you think GitLab is a good alternative to GitHub, I have 0 trust in you.
GitLab and Azure are a daily source of pain for us.