I'm not sure how much help I can be, but I'll give you my take. (this advice coming from a designer/developer)
There will always be room in this industry for great artists. The faster she can find her niche, the better. (at school or in the market)
(Pick a spot in the industry to study or work on... For example: 2D, 3D, concept art)
Whatever the route she takes, she needs to be focused on adding value. Keep doing actual work toward her end goal (and projects, as they will lead her to more profitable areas)
When she is looking at areas to study or grow in, I highly recommend she look on freelance websites like Upwork.com (or similar places) to find things that are actually in demand. (and price ranges) to make sure it's an actual area that makes anything.
(Advice to Her ^, advice to you \/)
But I think the biggest thing you are asking is, go to school, or do it on the side...
I would let her decide, but give her one condition... She has to set a time frame that if it's not working out within this time frame that she will do something else. (at least temporarily)
That way, her goals are real, and need to be acted on now or maybe never. (instead of checking Facebook again)
Whatever the case, I would love to see some of the art <img src="{SMILIES_PATH}/icon_e_biggrin.gif" alt=":D" title="Very Happy">
Also, https://www.youtube.com/user/ExtraCreditz this channel for any game designer (if that's the right term) has so much info that is definitely work a look for her!
I hope my rambling can be of some help!
Justin