It doesn't solve the number one issue: External references to your project will all still point to github.com since that's where the project homepage (aka README.md) is.
If GitHub does get sold to MS and I end up moving to GitLab, I'll probably push one last commit to the GitHub repo adding a header saying the project has moved, with a link to the GitLab repo. It's not perfect, but it wouldn't be too bad.
I expect Google could be convinced to accept certain files or metadata in a README as equivalent to a 301 permanent redirect, meaning searches will remain effective. That would account for a lot, especially if Chrome begins to honour it.
johannes1234321|7 years ago
mort96|7 years ago
jacques_chester|7 years ago
lemming|7 years ago