Now that's interesting. Moriarty is the author of the book that Big Little Lies is based on, while David E. Kelley wrote the TV scripts , so part two may be based on another book or simply find Witherspoon asking Moriarty to spin an entirely new scenario for the characters. Since Witherspoon is an exeutive producer on the show (so is Nicole Kidman), as well as one of its stars, she's certainly got the credits to keep it going if there is interest!