Our rule for our kids was that they stick out the sports season or series of sessions (dance/piano). We wouldn't let them leave a team in the middle of a season (except once when we pulled D1 from a team because of poor academic performance). And we insisted that they do something musical at least into the early high school years (but piano, an instrument, choir were all okay, whatever they wanted to do).
But after the season or session was over, it was pretty much their call. Once they get to high school there are SO MANY different things pulling at their time (and new opportunities like speech, debate, quiz bowl, etc.), our bigger problem was convincing them to drop some things so their lives and ours were sane. We were much more savvy about this with D2, so we were able to avoid overcommitting her in middle school. So the increase in energy required for high school sports and activities is managable for her.
I never consider the expense for travel/offseason teams an investment that I have to get a return on in the future. The one exception is if a sport required very expensive equipment. The one time one our kids did that, we discussed that they really had to stick with the sport for at least 2 seasons if we were going to put up that kind of money for equipment. Same with musical instrument purchases.
Once she really finds her passion, she likely won't "quit while she's ahead". I say let her dabble if she wants to.
