If the goal is for me to read the act as a horrible departure for Dexter into a world without rules, killing LaGuerta wouldn't fit, because I've wanted her off the show for years and she'd be doing a service. The property as a whole seems to have a pretty large hard-on for people bailing Dexter out at the last moment (see H.G. Wells), so I wouldn't be srprised if either Hannah or Deborah ended up pulling the trigger. I actually think, based on prior performance, that the solution the show will go for is this: 1. Deborah can't keep Hannah for a pen with no chain of custody on which any useful evidence has presumably degraded, so she gets out at some point 2. LaGuerta continues to nip at the ass of the entire series by hectoring Dexter, Deborah, and everybody else 3. Eventually, Hannah kills LaGuerta, bailing Dexter out of code infractions. She is either arrested or killed as a result. 4. Dexter somehow finds out that Deborah faked the poisoning as the big closer. That feels like a plausible conclusion to a season of Dexter to me, and it avoids taking any pieces off the board (last episode was the record high for the series), so if something goes squirrelly with Homeland or Showtime just figures out that they'd be idiots to cancel a show at the peak of its performance, which is the only sensible business decision. I mean, when EW is writing articles about whether you'll be dumb enough to actually go through with making the next season the last, given your ratings, that's a pretty good sign that the business folks might want to think twice about it, not in the least because if Dexter goes off the air and the network doesn't do comparable ratings with whatever it uses as a replacement (and this has been a much weaker season of Homeland than the first creatively, though that seems to have no implication on ratings for pay cable shows), that's a firing offense, whereas making the business decision to keep the show going without regard to creative won't have any implication if it turns out that the series immediately falls off and goes out on a fart sound.