EA has revealed that Battlefield 4 's third expansion, Naval Strike, will feature mostly water-based combat across four new maps. The expansion also includes new weapons, a new vehicle, and a new game mode called Carrier Assault, based off of Battlefield 2142 's classic Titan mode.
The expansion's site describes the Carrier Assault as a “re-imagining” of the Titan mode from 2142. Titan mode challenged ground troops to control missile launchers to attack a heavily armored enemy mothership , then board it and destroy the main reactor. Translating that back to the modern era might include anti-aircraft carrier missiles and boat- or air-based landing parties. I'm not sure what the present-day equivalent of launchpods are, but I hope that they make a comeback in some form or another.
Naval Strike will also introduce four new maps, set in the South China sea: Lost Islands, Nansha Strike, Wave Breaker, and Operation Motor. The expansion lands in late March for premium members, and two weeks later for everyone else.