If that is a big concern you can fork. If you are building production systems with dependencies on eggs you can't find in pypi you probably should take control of those in your own copies. I can't recall once that I had to do that for things that I ask money for though... if its not in pypi its probably not worth using. And if it is useful, forking or just copying the module or package into your own code base takes care of any shifting dependencies.

So yea, does not seem to be a problem that actually exists.