Dexter getting caught or killed and exposed has always been the obvious offramp for the series, but one thing that made Dexter interesting is the damage he leaves in the world while trying to project an image of harmless normalcy during the day and making his impulses a net positive for the world. They did a brief montage of the innocent people dead because of Dexter's damaged self, but implicit payoff for Dexter being uncovered was watching the damage multiply as the people in his orbit look back and realise what had been beside them for years. As an event I'm fine with it, but as a series end I have the same feeling I would have had if the season 4 ending had been the last episode they made.
Batista in particular should have had that - his part in the story is contrived (hey, the name Harrison is really interesting, right?) but when he literally grabs a file with LaGuerta's name on it and says he'll be there the next morning, I thought "this shit is going to be good." Remember, she was gunning for Dexter and he told her to back off before she was murdered. Deb confesses to him and he brushes it off. Of everyone still living in Miami, he's probably the best person to bring back for the fallout. When the show ends, he's still totally on his way, guys.
In a smaller way, Kurt's exposure as a last minute diversion wastes the same potential - the discovery of a serial killer within a tight-knit community would have been devastating, but we'll have to imagine. Dexter does have a habit of putting its finger on interesting themes or ideas then not putting in the work with them (single dad Dexter had promise until he just offloaded the ones who weren't infants, for example) and that's a shortcoming New Blood still has.
