The game will run on DICE's Frostbite 2 (the same engine that Battlefield 3 uses). Both single-player and multiplayer are going to use the latest version of Frostbite 2. It only supports Windows Vista/7 and DirectX 10/10.1/11.
The single-player mode will continue to follow the story of Tier 1 operators. It probably will take place after 2002. The single-player will feature Afghanistan, and it is based on real stories of Tier 1 operators.
Medal of Honor: Warfighter's multiplayer will not be developed by EA Digital Illusions CE who helped develop Medal of Honor (2010)'s multiplayer. Danger Close Games will develop its own multiplayer with DICE's Frostbite 2 engine, which in the previous game was not the case.
There will be a co-op mode, that is separate from the single-player mode.