Since the scene in the car, I’ve been hoping that Regina caved so quickly because she decided to play along, because it’d be easier to bring her mother down if they were in cahoots. I’d love it if Regina was letting Cora think she has all the control, until such time as she can strike, (which isn’t just yet, so I still think Cora will be the one who initiates the screwing over of Hook). I’ve never been an EvilRegal, but that’d make me respect Regina a whole lot more.
I do think that ultimately, the only way to stop Cora will be for someone to kill her, and that someone should be Regina. She already sacrificed a parent to doom everyone, and now she’ll have to sacrifice another parent to save everyone. The way things stand right now, it’s gonna take a huge gesture of some sort for the SBers to even begin to give Regina a real chance, and something of the magnitude of ridding them of Cora would do the trick.