My older daughter's problem is that she loves EVERYTHING. She is committed to gymnastics right now and doing ballet on the side. But every time she tries something new she wants to drop ballet to take up the new thing. Lately her new interests are kayaking, tennis, and karate. And she has always been interested in track and cross country. She wants to be a pole vaulter someday.
She is definitely going to learn to row someday, though she currently doesn't think so. It's DH and my sport, and it is big where we live. People move here to train for national team try outs. We have amazing youth programs that start around age 12, which is perfect timing for average age of quitting gymnastics. My DD is built for it too. But I accept that she may choose to reject the family sport. Though we will at least get her to hold an oar at some point, because we need her for our family quad. The great thing about rowing is that you can start in college and still get to the elite level, if you have what it takes. I am not saying I want that for my daughter, it just means there's no rush, as long as she remains active she can do it whenever. No need to start in middle or even high school.