I think this will happen...

The story will begin where last season ended. They will ask where's Trinity. Dexter will be prime suspect for Rita's death. Dexter MIGHT admitt killing Trinity to Debra after she confronts Dexter about why would trinity kill Rita. But that could be answered by Trinity was getting revenge for Christine's (Trinity's daughter) suicide.
With Trinity dead Dexter can't get revenge who knows what the unpredictable Dexter will do. I have to wait and see for that.
I think Debra might attempt suicide after discovering Dexter's "Dark Passenger".

I don't know what will happen obviously but I'm sure that this will be the last for America's favorite killer.

what's your prediciton????