I was asked recently to give an author's perspective on unreliable narrators to Dawn Ius of the U.S. digital magazine The Big Thrill which is the online publication of the International Thriller Writers. The blockbuster Gone Girl, closely followed by Girl on a Train has probably guaranteed that 'girl' has been exhausted as a book title for a while (particularly when you consider the earlier success of The Girl with a Dragon Tattoo) but what does it mean for unreliable narrators? As someone who has a protagonist who actually is a girl (I'd actually argue that Flynn and Hawkins' books are about women) who is an unreliable narrator, it is in my interests to argue that I think as a writing device they are going to be with us for some time yet.
I actually think that we are all the unreliable narrators of our own lives and that writing in a first person point of view allows you to explore another person's world, their boundaries of right and wrong from inside their head. A character's unreliability can be far more subtle than deliberately withholding information or directly lying to you. Using an unreliable narrator is a technique common to all genres of writing because it allows an author to explore our human frailty. So I think it's here to stay and even if marketing departments are a bit sick of them, readers will never be.
Here's the link to Dawn's article http://www.thebigthrill.org/2015/11/trend-watch/