With the final installment of Harry Potter now a done deal, rumours have been swirling faster than broomsticks at a Quidditch match that J.K. Rowling is working on her next book: a new detective novel.

"There are no firm plans yet as to what her next book may be," Rowling's publicist announced today to quell the rumour fury. She also stated that Rowling is "taking a well-earned break" after the publication of the final book in the successful series, "Harry Potter and the Deathly Hallows."

Whatever Rowling decides to write next, be it a detective novel, a thriller or a historical romance, it may not be the kind of fare her fantasy-loving fans have come to expect. As Rowling told The Associated Press last month, "I'll write what I really want to write." And she's got the mega-bucks to do it.

Thanks to her cash cow Potter series, which has sold more than 335 million copies around the world, Rowling is richer today than the Queen of England. Her fortune to date, according to Forbes magazine, is estimated at $1 billion.

Not bad for a one-time, down-and-out single mom who wrote the first drafts of her celebrated series in Edinburgh's cafes so she could save on her own home heating bill.

Certainly a detective story isn't that far a reach for Rowling. From deliciously dank snake dens to spider infested forests, this master of detail takes her Potter characters and readers anywhere she pleases to flush out a great mystery. And mystery is what Harry Potter, the young wand-wielding detective, is all about.

Yet like so many celebrities who have struck gold and exceeded everyone's expectations - including their own - Rowling now stands at a career crossroad, one where she may, or may not, succeed.

Can this wizard-loving wonder succeed at something new? Will her legions of fans embrace her next characters they way they've gone wild about Harry? They're questions her publisher and fans are certainly mulling over as they wait to crack the spine open on Rowling's next writing adventure.

Rowling herself believes she is unlikely to repeat the wild success of the Harry Potter series. According to Joanne Moyle, a Canadian marketing consultant and literary,  "I think she's established such a robust brand. I'm sure she'll have no resistance from her fan base if she takes on a new genre."

Such an artistic jump, as well as the controversy it will surely inspire once Rowling's detective tale is published, is not that strange. Writers from Charles Dickens to Candice Bushnell have been taking artistic plunges and living with the consequences, for good or bad.

Yet being so firmly attached to a money-making brand, as Rowling is, does present challenges. It would be like Sir Arthur Conan Doyle (the creator of Sherlock Holmes) churning out "Lipstick Jungle" or Dashiell Hammett (inventor of Sam Spade and "The Thin Man" sleuths Nick and Nora Charles) knocking off "Shrek." In today's brand-building world, turning away from a cash cow that keeps on giving is not always easy to do.

Rowling will write on, regardless of what critics may think.

"You don't go from selling over 335 million books to obscurity because you decide to try another genre," says Moyle. "I have a feeling Rowling will do just fine."

What do you think? Think she can make the leap to a different genre?