Rise of the Tomb Raider is heading to the PS4 soon and also getting a bunch of new DLC including a zombie mode at Lara's mansion (yes really) and an even harder Extreme Survivor difficulty mode.
There's also an expansion to Endurance mode, with the addition of co-op player. You'll always see yourself as Lara and the other person as Nadia (who appears in the story of the game) which is a little weird, and go out on mini missions where you mostly try not to freeze to death.
Here's a slice of co-op action.
Mechanically it doesn't seem like they've added a huge amount here, with little in the way of co-op actions. Still being able to sneak around and take out two goons at once, or distract a hulking great bear so your companion can shoot it in the face should be fun enough.
The new DLC is coming in October, along with the release of the game on PS4.