The beauty of `git clone` is that there are copies of the repository on many thousands of hard drives (including mine -- last pulled a few days back). The main loss at this point is the metadata stored in GitHub's proprietary addons, like issues.

We can hope this inspires a) greater suspicion toward proprietary players that are sitting atop open-source work like GitHub (they're not the only one by any stretch); and b) greater adoption of systems that distribute the software's entire history together, including documentation and bug reports, e.g. Fossil.