I've discussed that with her as well, though I'm not the best example as I did get the degree I intended to earn from the very beginning (and why I selected the school I did). This all came up when her school was trying to pin her down on a major when she was in Middle School and early High School. She was stressing out about it, so I pointed out how she'll likely change her mind several times as she gets older, gets exposed to more opportunities and ideas in life, and determines what she wants to do.
My advice to her on this has been to get a degree that gives her options so she can follow her aspirations. She has consistently wanted to be a teacher. I advised her to get a degree in a specific subject area and add a teaching certificate on top of that so she could be a teacher or work in another industry.
Chris