I'm a Senior Character Artist with 12 years of experience. Worked in several companies here in Montreal. My perspective is that you don't need schooling but, its better. It will teach proper anatomy, color theory and a bunch of other things that I see a lot of people often lack and fail to find a job easily.
Her concepts are alright but if she is serious about it, she'll need to show an exceptional ability to create any kind of concepts, whether is realist or more stylized.
Also, concept art is more difficult to get in comparatively to 3D art or animation.
Art in general and maybe specially for the video game industry means working really hard. Its a lot of hours to perfect your skills. So is she is serious about it, then she'll have to do a lot of extra learning and always look where she wanna be in a couple of years.
There's a ton of online resources like Feng Zhu school of design which offers some very nice videos for free. And also schoolism (paid but great)