Last year narrative designer Patrick Redding mentioned that a sequel would likely retain an African setting, but apparently that concept it is being tossed out the window. Antarctica has also been referred to as a possibility. It's also probable the game will be based around an improved version of the Dunia engine, a heavily modified version of the CryEngine specifically built to handle complex real-world physics within a sandbox environment.
So… to sum up we have no solid details regarding the setting, plot, game engine, or platforms, but it's still good to have confirmation for a new installment of Crytek's groundbreaking original. If you haven't played the series yet, Steam is selling the first two episodes for less than $30 -- or less than $20 if you act quickly and get in on their holiday sale.