Seriously, it will cause it to be too mainstream. Besides, you will run out of stories... Unless you just set it as Leviathan themed, and make Alex and Deryn go on random adventures in steampunked 1900 times. Then it becomes a regular cartoon, only in a diffrent time. I rather just have a movie adaptation of the 3 books.
Also, adding "The Animated Series" makes me think of the ultimate fail that is Transformers Animated. Maybe it failed BECAUSE "Animated" was in it's name...