They are de-facto "blocked" for developers that refuse to submit their identity to Google. I think you might not be understanding the implications of Google's policy, please read this open letter to learn more: https://keepandroidopen.org/open-letter/
If a developer doesn't submit to identify verification, under the new system their app could not be installed regardless of what store it is distributed on.
Needing individual devs to identify themselves directly to Google is invasive. Stores, however, could identity themselves to Google (or the world) as having security processes in place. Then they could be allowed as official 3rd party stores, similar to how the Linux repository system works.