I have to agree with Shweta. The DaVinci Code as their example of "deep research"? The document that the whole premise of the book is based on, the one from France in the Middle Ages, was proven to be a fraud. Any google search can tell you that. Sure, there's a lot of info in DaVinci, but does that mean it's "researched"? To me, researched means that the information contained in the novel is accurate (or at least mostly accurate and inaccurate only on small things that help to further the plot). Dan Brown based an entire book on inaccurate information, then went on a world-wide tour speculating on the possibility that his book might be right. Hell, he's got half the world believing Jesus fathered a child and got married.
Is terrorism the big thing in thrillers now? Of course it is! But does that mean that the terrorism thriller is on the way out because it's so overdone? Not neccessarily. Of course, full disclosure here: my first novel that I'm trying to get interest in is a terrorism thriller.
But it's just like the writer of the article said about the modern plight of mysteries: just when you say something is on the way out and everyone is writing it off, it makes a comeback. Publishers and agents are the ones who think they know trends. And, in some cases they do. But lest we forget, Grisham, who made the legal thriller successful (writing style and talent aside) was rejected by a goodly sized number of agents before catching on. The list of examples is endless.
Someone wise once told me, "if someone tells you they are certain they know how the world is going to turn out, bet against them." No one can predict what might happen in the future of books, or of the world. The terrorism thriller might be burning out now, but (God forbid) another attack or something like that could vault it back to the forefront of the world's collective psyche.