What happens to the forks when deleting the original repository?
It depends whether the original and the fork are public or private, according to GitHub's documentation:
- Deleting a private repository will delete all of its forks.
- Deleting a public repository will not delete its forks.
More detail on this page:
Deleting a private repository
When you delete a private repository, all of its private forks are also deleted.
Deleting a public repository
When you delete a public repository, one of the existing public forks is chosen to be the new parent repository. All other repositories are forked off of this new parent and subsequent pull requests go to this new parent.