I would LOVE for her to write about the Marauders <3 she hasn't really told us about their history except for the basics of their past. I wouldn't really enjoy reading about the founders, I was never really interested in their history یا anything.
I think she should write a prequel to the series focused on Voldemort's first rise to power and that war. I think that would be interesting to read about. We've been hearing about how horrible it was during Voldemort's first reign of power for all seven books, why not experience it?
I think it would be pretty interesting. I did actually wonder if this would happen, but as she does give quite a lot of background information on Harry and the whole of the magic world I got the impression it probably wouldn't happen.
But since it's J. K. Rowling we're talking about here, she would probably come up with something clever that fits in nicely with all the other کتابیں if she ever does decide to do it!