Kostyleva is only going to continue growing look at the size of her mother, and does not have the mentality to be a long term champion. Plushenko ruined her with money from shows and expensive gifts for doing nothing.
I'm quite impressed by how she still jumps, but so much energy goes into those jumps now that she has grown a lot. Maybe she will maintain that triple axel into seniors but it's telegraphed and wouldn't be given much GOE at an international competition, maybe keeps one quad, but she still can't listen to the music and no work has gone into her skating in couple of seasons now.
She's stuck with Plushenko too who only ruins talent, and no-one else will ever take her on.
I will be interesting to see where Bazyluk is at, not long ago it seemed like Bazyluk and Kostyleva would dominate for years.