FIFA 15 delivered a good experience with new timing and better team play, but the work for FIFA 16 started back in 2014 well before the FIFA 15 release arrived.
According to Peter Moore, "There are two phases to [development]. There's the core game itself. We have several hundred people working on that and it's a staggered development process, so there are already people working on FIFA 16." This came from an interview with CVG in late 2014, as reported by Console Monster.
With a year of work on the game and rumors of a new story mode there is a chance that we will see a big jump in features and gameplay in FIFA 16.