This has been a bizarre year for The Legend of Korra. First, Book 3 was released with little notice; then the show was yanked off the air and made an online-only property. Now the creators have announced that Book 4: Balance will premiere on October 3rd—of this year.
The creators did announce during San Diego Comic Con that production on Book 4 was nearly complete, but we had no idea it was so close to being ready for air. I suppose we should look on the bright side—we don't have to wait too long to see the next chapter in Korra's life. But releasing Book 4 so soon after Book 3 is another perplexing move on Nickelodeon's part.
Like the latter half of Book 3, Book 4 will premiere only online, not on television.