Oh god forbid anyone at Ghibli should get their claws into Obernewtyn, especially Miyazaki! Don't get me wrong, I love Ghibli films, but the thing I love most about Obernewtyn is the complicated storyline, and Ghibli, and Miyazaki in particular, has a reputation for putting theme and style before plot. Case in point: Howl's Moving Castle has very little to do with the Dianna Wynn Jones book it was based on. I'd HATE to see that happen to Obernewtyn!
personally I hope the Ober Chrons never become movies. This is mostly because so much of the story revolves around abstract images that I just don't think would translate well to film.
I like to think he did a pretty good job of slicing out a couple of unnecessary tid bits and plot lines, where a lot of other book based movies have gaping plot holes *coughHarryPottercough*
This isn't the first time I've heard a suggestion for anime, my best friend and I have said it multiple times. I can see where you're coming from with the kawaii female characters, but usually it depends on the genre. I don't see Obernewtyn being made into a moe or mahō shōjo series...I picture something a lot more stylised, like Howl's Moving Castle.
I can also see Elspeth being represented like Major Motoko Kusanagi from Ghost in the Shell: SAC