Git is decentralized as is. It stores all the history locally and sends a copy to GitHub AND/OR any other repo you would like. GitHub is just a part of decentralized git ecosystem. It simplifies communication. But I agree - it is good to use more than one repository. And in case of Bitcoin code it is crucial to use several different private repos owned by different people.
But why such control is being spread amongst countries to stop specific places from using something that allows usage of open-source applications? If this is being stopped, what's the guarantee that in the near future, these 'laws' are not going to stop you from doing other activities too? Then, where is decentralization and if such solution doesn't/ can't exist, I don't think that such technologies will be evolving any further.