Rawhide is a bad comparison to use. CentOS Stream will never get any major fundamental changes to the system like Rawhide does on a regular basis.

It's technically rolling release compared to RHEL, but the window of acceptable changes is very small. It's not like Arch and Rawhide and Debian Testing where major OS components can be swapped out under your feet. The majority of the changes would fall into the categories of bugfix backports, backports of extremely useful/important features, and backports of support for new hardware.

This is not even remotely what the announcement is implying.

CentOS is the new upstream for RHEL minor releases. Fedora is and will continue to be the the RHEL upstream for major releases.

Lifecycle of RHEL:

  Fedora 
  |
  Enterprise Linux Next*
  |
  HARD FORK for next RHEL
  |
  Centos Stream (Pre-release phase)
  |
  RHEL Major release
  |
  CentOS Stream
  |
  RHEL Minor release

Those last two will loop until the RHEL full support phase (first 5 years) are over, at which point Stream will end due to there being no more minor releases. Any consumers of Stream will need to migrate to the next major version of Stream.

Stream will have effectively 6 years of support (5 + 1 year pre-release), and RHEL will be releasing major versions every 3 years.

Considering new technology and design decisions aren't incubated at all in CentOS, it is in no way shape or form possible to use it to replace Fedora.

* ELN: Fedora Rawhide with RHEL buildroot context.

Has it though? How many companies have moved from centos to RHEL?

Yes, RHEL Workstation exists. Not sure I understand your point though?