This is disappointing news indeed. I figure our best hope is that E+ space opens up late thanks to upgrades clearing. If I wasn't well on my way to MM status I would seriously consider bailing. Priority security line access is about the only 2P perk left.
One potential unintended consequence of this is you might see people asking the gate agents for a last second seat change. I know many agents don't like being "bothered" but I hope they get used to the new policy result.