I don't think Deb has the emotional fortitude to keep this kind of earth-shattering secret under wraps for very long. I think she's going to turn to alcohol, or pills... or both, and that will make her sloppy. I'm not sure whether she will just reach her breaking point and consciously decide to drop the bomb, or whether she'll slip up (either drunk or sober), but I feel confident that his undoing will be by this weak link, and not by his own error.
- Dexter does not get locked up
I think Dexter will prevail in the end. He may end up being a fugitive, or in a different country, but I don't think he'll end up behind bars. After all this time, I believe the writers are going to leave Dex mingling among the general public, and his specific final fate to our imaginations.
- Dexter kills Vogel
Dr. Evelyn Vogel is a new character appearing in season 8. She is "an intelligent neuro-psychiatrist that specializes in working with young psychopaths and profiling criminals in unorthodox ways." So, obviously, she needs to die. I think she'll start to unravel Dexter's tightly wound psyche, and begin to get in his head. There, she will find herself in way over her head, and eventually lying on her back under plastic wrap. The problem: she won't deserve it, and this will only further serve to shake Dexter's principals.
- Dexter kills Deb
I think this will happen. I think she will put him in the position where he will have no other options, and he'll ultimately choose himself over her. Whether or not he will have to take out any of the other main characters in the meantime is difficult to say, but I have a pretty strong feeling about Deb.
- Dexter loses Harrison
I think something is going to happen to Harrison. This event will exacerbate Dexter's already precarious control over his Dark Passenger, which will lead to Deb needing to go to more and more stressful lengths to "cover his ass." That is where we have the possibility of Deb reaching her breaking point and spewing out the ugly truth about Dexter to, if I had to guess, Batista.