Expect announcement next week
While Battlefield 3 is still going strong, we know that DICE and Electronic Arts have more downloadable content planned for release. DICE has said a couple of times that they do expect to release more content for Battlefield 3.
While sources are quiet on what the new DLC content could be, it is expected that the announcement will come next week in New York City at an Electronic Arts event. If rumors are to be believed, DICE has an All American content pack on deck that will feature maps in a number of city locales in the U.S.
Look for the official word to arrive at some point next week.