Harry Potter - The Marauders?

I think she definitely could. There's so much that JKR could write about. That little 800 word prequel she did for Bloomsbury would be a great start to a novel about the Marauders and she actually said that while she was writing that, she was surprised by how easy it was and how excited she got. So I think there's definite chance of her writing more books about the Wizarding World sometime in the future. I mean how can she resist??!