Yen Press, a United States-based localisation company for Japanese manga and novels, have revealed on their Kingdom Hearts page that they will be releasing Kingdom Hearts: The Novel sometime in March 2015. Kingdom Hearts: The Novel will be 300 pages long (at a size of 5-1/2″ x 8-1/4″), and will be available for US$16.00.
Update: Barnes & Noble have confirmed that it will be released on March 24, 2015.
The novel is listed with artist Shiro Amano and writer Tomoco Kanemaki, indicating that this novel is likely a translated compilation of the first two Japanese Kingdom Hearts novels, The First Door and Darkness Within. The following novel description was also published:
On the Destiny Islands, three children–Sora, Riku, and Kairi–are living out their peaceful, carefree lives while yearning for whatever lies beyond the great ocean. But one night, an unexpected disaster takes place, and the three are torn from each other and their island home. Meanwhile, at Disney Castle, Donald Duck and the other castle residents are in an uproar upon discovering King Mickey has suddenly gone missing. When fate brings them together, Sora, Donald, and Goofy set out on a grand Disney adventure to find their friends!