No details have been released about the title or what it will be about, but the publisher switch came with this statement: “Although I've enjoyed writing it every bit as much, my next book will be very different to the HARRY POTTER series, which has been published so brilliantly by Bloomsbury and my other publishers around the world”
“The freedom to explore new territory is a gift that Harry's success has brought me, and with that new territory it seemed a logical progression to have a new publisher,” she continued. Her last book was released almost five years ago, and it broke sale records.
Considering the first book was published in 1997 (1998 US), most of the original fans of the book are now into their adulthood anyways. Aside from that, many adults became fans of the series through its publishing process.
Aside from that news, Rowlings original publisher, Bloomsbury, is also planning to publish illustrated versions of all seven HARRY POTTER books starting in 2013. Seems strange, since we’ll have the movies and won’t need the illustrations, but we’re excited.