Interesting... I enjoyed the film and she was superb but I really don't think a sequel is necessary AT ALL.
The film sort of wrapped everything up. Besides despite enjoying the film for what it was, viewing it as a 'prequel' to Sleeping Beauty still drives me mad seeing as they completely changed the storyline
If anything I'd rather they scrap this and start doing Wicked-esque re-tellings/prequels of the other Disney villains... starting with Ursula!!