I love this idea, they could just keep raising the bid until they get enough takers. But this could also be turned around to screw the passengers: what if they made YOU bid to keep your seat? How badly do you want to get to where you’re going on time?
And tell me that United is not nailing people left and right for changing a ticket. I paid $300 last time just for the privilege of changing a date, months in advance of the departure date. A more unsympathetic business organization is hard to imagine.