Brand Over-Extension?

In the wake of the success of The Dangerous Book For Boys which I blogged about some time ago, it's inevitable that The Glorious Book For Girls is being created for publication next summer.

Where I suggested that the Boy's book was being bought by grown-up boys harking back to childish days, I wonder if the Girl's book will be so successful. Are today's young girls at all interested in innocent pleasures that do not involve celebrity, accelerated maturity and crucially have no digital component? Moroever, are older women likely to want to relive those aspects of their life - and do they indeed have the time?

It is an obvious move to create the female version, but does it show an understanding of why the male version succceeded?