If you look back through the years and find a few other stories of "GitHub is down", you'll see that this conversation happens every time. Some people tread into the HackerNews thread and say "More people should be using self-hosted GitLab instances" or "if GitHub would just open source their code, we wouldn't need to be so dependent."
But then the conversation stops within days because, the fact is, hosting your own git servers and getting people to actually use them is a huge pain in the ass. More simply put: people just like using GitHub.
Furthermore, GitHub's a business. They're selling private repositories. They do open source quite a bit of code, but they're not going to open source their actual product.