The original CentOS founder already announced his intention to do exactly that. I believe it's going to land here: https://github.com/hpcng/rocky. The thread about the CentOS Stream announcement yesterday had references to other efforts too.
Theoretically, CentOS was the RHEL source release.
Now that this changed, I wonder, do RHEL sources are still available 100% identical to their binary? Or the announcement yesterday just broke GPL2 compliance?