There's a possibility that this isn't the big deal people think it could be. It all depends on the day to day stability of Stream. Red Hat distros already have a testing repository channel for example. If stream updates are QAed through something like this the resulting platform may well be stable enough for many use cases. It would be no different to enabling the 7x/8x repo in the current releases.
In many respects I'd rather have a slow trickle of updates than the current flood of each point release. We've had lots of experience of dealing with all those changes landing at the same time breaking things.