The Western Expansion
Electronic Arts and Visceral Games proved that the series didn’t need to take on a strictly military theme to succeed thanks to Battlefield Hardline. This means it’s entirely possible for a Battlefield game set during the tumultuous period of Western Expansion in the United Stated to succeed. Similar to the American Revolution, there could be a number of different factions at play including American settlers and cowboys, criminal gangs, U.S. Army troops, Native American tribes, and more.
Such a setting could also allow for a more free-form story campaign that showed how the expansion affected the different factions at play, which in turn would give the game’s multiplayer component some added depth. Either way, such a Battlefield title would, at the very least, help to correct the fact that the Wild West is a sorely underutilized setting in video games these days (upcoming games like Red Dead Redemption 2 notwithstanding).