This video offers the first developer diary from XCOM the upcoming X-Com revival in a clip titled "What is XCOM?" They call this a "really beloved franchise" that 2K Marin – Canberra is looking to "reinvigorate...with a new entry that really adheres to the tenets of what made the original game so special," in spite of the change in genre from a turn-based tactics game to a first-person shooter. "Our telling of XCOM is an origin story. It's about experiencing the origins of this organization from a really zoomed in and boots-on-the-ground perspective," explains Jonathan Pelling, lead designer. "We really wanted you to feel like what it was like to be one of the squadies in the original game, and not the all-knowing, top-down commander."
So what about these tenets to which they are adhering? "We've taken a lot of the mythos that had previously been established, and sort of re-imagined it, or re-engineered it," says Morgan Gray, development director. "Like sort of the very small humble roots of the organization before it became this globe-spanning, globally funded anti-alien defense force." The diary goes on to offer more details about the game's alien invasion and the unusual nature of the organization combating it.
To me the key aspects of the original XCOM was the tension throughout the game, along with the ability to recruit/develop my team, and to find/develop new tech (the psi powers were especially fun).
The turn based game mechanic was secondary, although I believe turn based games can be successful.
I am willing to take a wait and see approach to see if 2k can deliver.
Shameless plug alert: I discuss this in more detail on my own blog