GitHub offers free unlimited private repositories
Only up to three collaborators, though.
I doubt there were that many individual developers having paid GitHub accounts, so there’s no money being thrown away here. Most people that used to pay for their account will still be paying.
What else will happen? Tens of thousands of BitBucket accounts will suddenly be abandoned and their holders will move to GitHub to grow until they need a team subscription.
GitLab will hang on alright.