I bet you that Quinn figures out what Dexter is, tying it back to the Bay Harbor Butcher, the Ice Truck Killer, and Trinity, and Deb will either A) Kill Quinn to protect Dexter or B) Arrest Dexter.
They didn't get into it here but don't forget that Deb last season was THISCLOSE to tying Dexter's mother to Harry, which leads to Brian Posner, the Ice Truck, her, and full circle. If she can figure out, then Quinn (who I think is a better detective) can and will. Dexter is going to have a completely shitty season, his masks are done for, and his willingness to kill innocents and act emotional in front of others:
strangling/preparing to kill Arthur in the kitchen;
flipping out on the county police;
punching the neighbor;
being sloppy with kills all over all last season;
killing the guy in the rural bathroom last night (!!!! Killing the fashion guy is a little less worse because he did it his usual way in not leaving any evidence. He didn't even wear gloves and we don't know if he disposed of the body);
killing the wrong killer in the fashion designers';
everyone beginning to notice and comment on his constant absences, from family to friends to co-workers;
and setting an arsonist blaze in a property he rented that can be tied back to him in a desperate moment are all going to come back to bite him. Looking back on the series he's gotten ever sloppier the longer he's been with Rita. I think it's finally going to all come crashing down. He's been leaving loose ends all over Miami and beyond since Brian kidnappped Deb, and he's barely covered it up:
S1: Brian Posner. Deb can tie all this together at any moment.
S2: Doakes was just dumb luck. His overseas trip could tie into Lila's death/vanishing. Multiple people I believe know about Dexter and her.
S3: Miguel's death, tying Dexter to the Skinner.
S4: Dexter is all over Trinity, and the FBI is all over everything.
It's seriously just the barest of separations keeping Dexter apart from all of these events and three serial killers (Skinner, Bay Harbor, Trinity).