That would be cool, but what if it was horrible? If it fails, then all us fans are sad forever and they ruined it. Plus, thy'd have to get differant actors...
Series? Not sure... If they do more justice to the novels than the movies did, than maybe. I am a bit allergic to "milking out" a success, which has happened to many many great franchises, and I'd hate to see that happen to Harry Potter.