While update 0.15.4 has just been released, the next update has already been officially confirmed. One of the lead developed of Minecraft Pocket Edition, Tommaso Checchi, posted on Twitter confirming that the next update for the game will be 0.16.0
Very little information has been announced so far but some of the additions have been hinted at and rumors are already suggesting what will be included in update 0.16.0. The biggest addition will be the Deep Ocean biome which already exists in the PC version of Minecraft; the new biome would also include Ocean blocks and monuments along with the Guardians mob which spawns in Ocean Temples.
There is some thought that Polar Bears would finally be added to the Pocket Edition; this mob has been hinted at for quite some time and a Twitter post confirmed that they would be added to the game some time after the 0.15.0 update.
Players should also expect to see new Resource packs being added to the game along with some tweaks being made to the settings and general game layout.
More information about the upcoming 0.16.0 update will be revealed as the expected Fall release date comes closer.