Um . . . I'd like to mention that "futuristic" isn't necessarily synonymous with SF. A futuristic thiller CAN be science fiction, but certainly doesn't have to be. It merely needs to be set on good 'ole Earth. SF generally includes the use of science in the plot and resolution OF the plot and often is set off-Earth.
This is one of those craft vs marketing questions I think.
From a craft perspective we can't differentiate thriller or SF by setting -- although both often use exotic locations. What makes a thriller is its dramatic structure. What makes a story SF is its science/tech frontier plot content. You can set either of them anywhere. A great deal of SF is set on Earth: virtually the whole Cyberpunk genre, for instance, and Steampunk etc... not to mention books by pioneers of the genre like Wells, Verne and Shelley, which were nearly all set on contemporaneous Earth.
But thriller-writing is a dramatic technique you can apply to almost any premise: romantic encounter (
Fatal Attraction), murder mystery (
Silence of the Lambs), religious intrigue (
Da Vinci Code), corporate intrigue (
The Firm), travel adventure (
The Beach). [For a bigger list see
here]. For sample SF thrillers, consider
The Invasion of the Body-Snatchers,
The Stepford Wives (the first one) and
Alien. All use the classic thriller formula of a looming atrocity; excited, fearful, almost paranoid pursuit; headlong pace; and either a lit fuse or options dwindling to the unthinkable. All are nail-biters. All are SF because of the premises, and some are arguably horror too.
While these stories are all thrillers in a craft sense, for marketing purposes you might only find them on the SF or horror shelves -- because ordinary thriller customers often prefer their stories to be about the familiar. But thriller-genre specialists push the credibility envelope themselves all the time -- e.g. Crichton's space-germs or Brown's antimatter-bomb.