Of course it still sucked when some tool decided I needed to update dependencies which all lived on regular Github, but at least our deployment stuff etc still worked.
That decision proved wise many times. I don't remember CodeCommit ever having any notable problems.
That said: if you're using GitHub in your actual dev processes (i.e. using it as a forge: using the issue tracker, PRs for reviews, etc), there's really no good way to isolate yourself as far as I know.