I'm sorry but where does this "one year" expectation come from? What says that Waymo needs a year (or two years, or ten, or three months, etc) to start "scaling back the drivers"?
From what I can tell, the only way to judge the competence of their driverless systems is to compare where they are today with were they were 10 years ago when they started out. However, this is next to impossible- that data is not public.
So, where does that "one year" optimism come from? Autonomous driving won't magickally become easier in a year from now.