Originally Posted by Bowgie

Yes, it is not a new rule. Been that way for years. Board you lose. If you are on the bubble, I'd hang back and check with the GA after everyone boards.

That's not to say a GA won't ever come on board and upgrade #1 just before the door closes. I remember an ATL-AUS flight about five months ago. The Delta app showed me about four below the one available upgrade. So I boarded early. Later GA comes on board and upgrades me.