EA Games VP Patrick Soderlund has been talking to OXM about the various projects underway at DICE right now, and it sounds like there's more going on beyond Battlefield 3 DLC and Battlefield 4. "The DICE guys are roughly 300 people in the Stockholm studio," said Soderlund. "Not all of them are working on Battlefield things, and that's intentional, because we don't want to become a Battlefield factory."
"The minute we start saying 'you're going to make a Battlefield game for the rest of your life', they're going to go some place else," he added. "So for them to make great Battlefield games there need to be other things for them to do as well. That's why we have people who move around quite a bit.
Update: Regarding those other projects, "Mirror's Edge 2 is in production at DICE," says former Battlefield producer Ben Cousins in a tweet spotted by PCGamesN, a fact that is supposedly "general knowledge in the Stockholm dev scene."
But what could those non-Battlefield things? My hopeful heart cries "Mirror's Edge 2!" but that's something it does every few minutes whatever the news (the update above gives me even more hope). The Frostbite engine is being used all over EA now, it's also possible that DICE's engineers are also working with the likes of Bioware and the Need for Speed team to help them get the most out of the new tech.
Battlefield 4 is due late next year/early 2014. If it's playing by BF3's model that'll be followed by a year of DLC leading up to Battlefield 5 or a new Bad Company, but it's impossible to know just yet. A year is a long time in FPS land.