It's got to be done, so may as well test it ...
The FAQ says to do:
dnf install centos-release-stream dnf distro-sync
This I did and everything went fine. I checked before doing the distro- sync and there was a load of new Stream repos in /etc/yum.repos.d
Rebooted the machine and dnf has gone back to only looking in 8.3, and the stream repos had disappeared.
Looking in the logs I can see this:
2020-12-09T12:28:42Z DEBUG ---> Package centos-stream-release.noarch 8.4-1.el8 will be installed 2020-12-09T12:28:42Z DEBUG ---> Package centos-linux-release.noarch 8.3-1.2011.el8 will be obsoleted 2020-12-09T12:28:42Z DEBUG ---> Package centos-release-stream.x86_64 8.1-1.1911.0.7.el8 will be obsoleted
and
Installing: centos-stream-release noarch 8.4-1.el8 Stream-BaseOS 21 k replacing centos-linux-release.noarch 8.3-1.2011.el8 replacing centos-release-stream.x86_64 8.1-1.1911.0.7.el8
The centos-stream-release RPM does not contain any repo information, that was all in centos-release-stream that has been removed. So stream has deleted itself.
It's not a good start.
I also can't seem to get back to a sensible system and have now got a system with a mixture of CentOS 8 and CentOS 8 Stream RPMs with no way of installing the Stream repos from an RPM.
I see that "subscription-manager" has been installed on this system now which it never was. Is CentOS also going to be part of that ecosystem as well?
Fortunately this was a throw-away install. I hope no one has tried the instructions in the FAQ on an important machine!
P.