A Wrinkle In Time has always been a difficult book to adapt, as the various TV movie versions can attest. Personally, I think Rob is extrapolating that because Lee wrote Frozen that this will be a musical, and I really don't know what he means about "Frozen-Style update."
The two things I really, reallly hope they do are a) not "pretty up" Meg, or play her as being misunderstood by her family. Her family encourages her, and that's whats awseome. b) get the relationship between her and Charles Wallace right. It's so rare that you have realistic sibling relations in a movie.
in fact, I really think they should make it a period piece - no ipods or video games.