The beauty of git and similar DVCS's is that you essentially can't lose the repository. You can only lose the github namespace for that repository. And using a different platform has the same effect. If you are worried about losing the Github namespace for the repository then moving to a different platform doesn't seem like a solution.
issues, pull requests, deploy keys, access control. None of those the repository. They are associated with the repository and it would be annoying to lose them But with the exception of the issues all of them are replaceable with mostly minimal effort unless you did something really wrong.
And again switching to a different platform doesn't solve that problem either. You'd still lose the issues that are in github.
