The movie is based on the concept of man's breaking of barriers; this time, just as we broke the sound barrier, we'd be breaking the light/time barrier. The film is based on Kip Thorne's lectures on faster-than-light travel and their immediate implications for anyone involved. Because you see, if you actually were to move truly faster-than-light, you'd be moving faster than time propagates... This means, in essence, you'd be catching up to previous events, and thus, moving backwards in time (time travel, into the past).
This is the basis of the movie, and likely McCaughney will have to wrestle with this phenomena at some point (if not throughout) the film.
Originally, Steven Spielberg was set to produce/direct but Christopher Nolan has taken over the project and begun to humanize the story. Originally it was to be a sci-fi film mostly set in space, but now it seems that it has taken on a much more human, personal and interpersonal context. So, while being science fiction, it will likely be more like Inception than Gravity; both having a science fiction base, but definition not being the same genre of movie.
If I were to venture a guess, I'd say Nolan might revisit the narrative style that made him famous in Momento and put into into an actual temporal context of disjointed events. But again, that's just a guess.