I just read an interview with Scott Buck the executive producer of Dexter. He commented some on next years Season 8 and a few other loose ends.
He said LaGuerta had to die to show Dexter was a serial killer and not some kind of super hero. Bringing Deb into his web was one of the first steps toward the end of the series. He said it is impossible to undue Deb killing LaGuerta. It leaves a big hole in the show and he said they will not try and fill it. Rather this next season, and he last, will be Dex in full free fall and they will explore the things that happened to Dexter that made him who he is today.
Buck also clarified to TV Line that the black orchid that Hannah left on Dexter's doorstep was meant to be taken "as an ominous goodbye" that signified her plans to take revenge, and told THR that he's hopeful Yvonne Strahovski will return to the show next season, although her contract has not yet been signed.
He also noted that while the show's producers are writing Season 8 as if it will be the series finale, they haven't yet received final confirmation from Showtime that it will be."
The crazy part about Showtime ending the series is Season 7 was the highest rated of any of the seasons. Most believe because the show was paired with Homeland. They drew over 2 million an episode and for a premium channel that is amazing.
Could we see season 9 of Dexter. I don't think so but some wonder why Showtime hasn't formally announced the end.