At the ongoing Halo Fest, 343 Industries announced that the new Halo trilogy, featuring Halo 4, 5 and 6, will be called The Reclaimer Trilogy. The little, round AI probe in the series called Guilty Spark (also the namesake of 343i) is often called the Reclaimer.
343 have also announced the game will have much larger focus on Master Chief, Cortana and 343 Guilty Spark.
Stay tuned for more info.