Polina A won't likely ever be tall but she could become too sturdy to keep those difficult jumps, especially if she stays very short. A lot of skaters receive downgrades for 3-3s once they fill out. A lot of Russian women are short and stocky, some Russian coach even said that most Russian girls are built to work on the railroad. This is why I think Polina S and Anna have more potential, they have the ideal body type for skating and will likely still have the ideal body type once they finish growing just judging from their frames. This is also why I think Gao has potential to become really good in the future too because I don't think puberty will be an issue for her where she is so thin now at 16. I actually think for Gao puberty will help her become a stronger skater. Gao, Shelepen, and Ovcharova are substantially taller than Agafonova, Murakami, Baga, Tuktumysheva, and some of those other really young Russian girls and usually, girls that are tallish and thin at that age can fill out but still stay very lean while shorter girls can become stocky because their muscle is more compact, and this can effect spirals and spins as well as jumps. Gao, Shelepen, and Ovcharova I doubt will have issues with puberty, but Murakami, Agafonova, Baga, and some of those other Russian girls very well might.
Well here are some clips of young skaters some who became successful seniors some did not
Shizuka at 13 http://www.youtube.com/watch?v=7dVd6N_0yRY&feature=related
Irina in 1993 http://www.youtube.com/watch?v=e00A9aXMEzQ
Naomi Nari Nam http://www.youtube.com/watch?v=1S7EEHAM6nU
Sasha Cohen http://www.youtube.com/watch?v=OpZE4Hemcrg
Katy Taylor http://www.youtube.com/watch?v=3LiKzP6sy2U
Elene G (who we all know struggled with puberty) http://www.youtube.com/watch?v=PuNpzXq_U3k&feature=related
Kimmie Meissner (struggled with puberty when she got a little older) in 8th grade
http://www.youtube.com/watch?v=rhSCs72lDPs
Yukina Ota http://www.youtube.com/watch?v=3lcUcvHpPQM
Jenny Kirk http://www.youtube.com/watch?v=p1rXt9n_3V8