I'm pretty sure the GA still has some level of control. One scenario may be when someone is auto-upgraded at T-40 minutes, but is a no show (flat tire, drunk at the bar, late connection, etc.). Then the plane boards and it's T-15 minutes with one or more empty seats up front. Now the GA sees that F pax have not boarded and they have to get the door closed in 5 minutes. Will the GA take the time to roll the next person(s) on the list from Y to F, or will they ignore it in the interest of achieving D0?

I propose we sticky this thread so people can share various experiences as this new process rolls out.