Harry is Dexter's good conscience, "rulesmaker" that he feels he needs. He's only there because Dexter places value on that. Zach doesn't like the code because it preaches patience, and now is not on good terms with Dexter because of the neighbor. He wouldn't want Dexter back after his death unlike how Dexter wants Harry's guidance, so I really wouldn't enjoy that an ending.
[COLOR=#red]CP[/COLOR] your post got me thinking. What if...
We know Harry talks to him when he's dead, Rudy did, another person you would call Dexter's family. What if Deb has been dead this whole time (in Sixth Sense fashion) and we find out that out in the last episode. She is dead, and like he has with Harry, Dexter now has been talking to Deb as well all 8 seasons of the show, and we all just thought she was alive, a figment of his imagination just like Harry. He is a psychopath, says Vogel, right? Deb WAS Dexter's actual first kill.The reason Harry felt like he couldn't "live with what Dexter did" is because he witnessed Dexter killing Deb in the kill room. So he killed himself.
Remember, neither Dexter OR Deb have seen ALL of Vogel's tapes with Harry in therapy. The tapes we haven't seen yet are him talking about it being Deb, and such. How it's such a burden.
What an ending that would be....