That probably depends, how strongly Stream and RHEL actually are going to be linked. If this relation is indeed similar to current situation, but centos and RHE

That probably depends, how strongly Stream and RHEL actually are going to be linked. If this relation is indeed similar to current situation, but centos and RHEL changing places, then there isn't much point holding QA until RHEL release. Actually, there is going to be good initiative: when you upstream is unusable, because too buggy and untested, then what? Whole point of Stream seems to be usable base to RHEL.