[user104658]

Yeah I don't think another season would work - I could see them trying to do it with Dexter still in it, as the new Harry/Deb "on Harrison's shoulder" but I agree that it makes no sense - the overall impression I got from the show was that Harrison actually wasn't like Dexter - or even that DEXTER didn't have to be like Dexter - that with help, therapy for what happened to them as children, they could actually have overcome the darker urges. That was hinted at right from the start - Dexter successfully lived a normal life in a normal community for several years without needing to kill.

I feel like Harrison constantly trying to justify it as them helping innocent people, not being able to handle being in that bunker for the dismembering, being horrified that Dexter had killed Logan, showing some guilt/remorse for what he did to Ethan, etc... as well as having clear genuine affection for Audrey and wanting that family unit with his dad and Angela (whereas Dexter was pretty much always faking his connections)... shows that he was never quite on that same path, and it was somewhat "wishful thinking" from Dexter. He was into the "hero vigilante" idea somewhat but he saw it for what it was in the end - an excuse to kill with as few consequences as possible. He helped Dexter to see that in the end, too.

To retcon all that and have him become a killer would undo the whole narrative ... which was actually rather good.

HOWEVER I have read that the viewership is extremely high for the network it airs on in the US (Showtime) - the highest in the channel's history - so it's likely that the channel itself would have been keen for more. If Dexter himself wasn't dead I'd have said it was a certainty. They might try anyway which would be ... a shame.