For the rest of us mortals, just getting published is the challenge, in part due to the entrée of celebrities like Katie Couric, Madonna, Paul McCartney, and others to the genre. Whether or not they can write, they have name recognition that helps sell books--lots of them.
Call me grumpy, but I think it's probably not worth asking whether you--or anyone--could be the next J. K. Rowling. The odds of having your own messenger owl and a turbocharged broomstick are probably just as good.
That said, there's a better question to ask yourself: Could you write books for kids at all?