Honestly, I don't think the revelation of Dumbledore's sexuality has anything to do with a new series. At least, my faith in her as an person who takes pride in her work says so. [EDIT: To clarify, I meant in terms of using it as publicity before a new series. I personally have nothing against homosexuality.] However, I'm not a fan who has followed the series, so I don't know her mindset; I've watched all the movies but the newest one, but I've never read any of the books.
I think it would smart for her to keep the universe, but focus on a new set of main characters while previous characters make cameo appearances. Something to separate it from the previous one. There's nothing wrong with revisiting a universe as long as you do it well. When I was young, I got hooked to the Song of Lioness quartet by Tamora Pierce; Pierce has revisited that particular universe in several series since, but she did it really well by looking at it from a new angle each time. Granted, it was nice when old favourites re-appeared in the series, but they never became a focus, which I think is important if you want some longevity. You also got to see old favourites mature and one of the newer series focuses on the daughter of the first series' protagonist.
Before I go on too much of a tangent, my point is that it's possible to do it; as long as it's done well and you don't let anyone looking to make money off you corrupt your integrity.
