I’m not convinced that Archie will die, although I do think it’ll be him who will “disappear”. Maybe Cora turns him into a fish and tries to pretend he’s dead and blame it on Regina, like lots of other people suggested.
The execution part is in FTL, I’m almost sure. It’s probably time to give us some flashbacks on how exactly Snow and Charming went from a couple of runaways to King and Queen. We only see them plotting and briefly fighting that war in one or two flashbacks, but we really have no idea how they defeated Regina, so that’s probably what this episode is going to show.
It would be a nice parallel too if the FTL flashbacks showed Regina being convicted of crimes she did commit, and, in Storybrooke, being unfairly accused. Also, she obviously got away. Wonder how that happened… 🙄