I think it is really common among the gifted kids to just have a strong interest and joie de vivre about lots of subjects.
In my experience, if you choose a path at 15 and do the prep work for a potential career, many of those courses will still point you to a good variety of choices.
FWIW, I was pre-veterinary, then a French major, then Communication Disorders (only because my friend said I wouldn't have the patience to do therapy! HAH), I had 5 minors in college and took 1 year longer to sort it all out.
If your child goes to a larger university with so many interesting choices it may be really hard to choose, but she will one day!
I'm still sulking about not getting to fit beekeeping and orienteering into my schedule!

i could have been a student for 10 more years and been happy happy happy.