@dennisbon Offering my perspective as a child of parents (well, one parent) that placed a lot of value on athletic excellence: Don't do it. Well, don't do it yet, and if you do, don't break your family for one child's athletic "career".
There is not a single reason to push a child into the intensity of traveling sports that young. If your child wants to dedicate a lot of time to a specific sport, is showing promise in that sport, AND (most importantly) it's within your family's time and financial budgets, it's okay to do those in middle/high school, but never do them at the cost of the other sibling being miserable.
My younger sister and I were more athletic than most, but she was much better at team sports. My parents started her in traveling softball when she was in middle school. I played one season of traveling softball. We both had fun that one season, but I wasn't interested in continuing as it wasn't my primary sport and I didn't enjoy spending my entire summer at miserably hot ballparks. She kept playing for several years, even after starting on the JV team. We had only just gotten to a place where we were able to go on larger vacations as a family, but that was quickly squashed because our entire travel budget was spent on hotels for tournaments in crappy suburbs every other weekend. My sister did well and had offers from some small colleges, but it was her performance on the varsity and all-state teams that attracted the attention of recruiters, not her time in traveling ball. She also didn't play softball in college because she wanted to focus on academics.
For my family, we only have a singleton, so I won't have to worry about where a sibling fits into those plans. But I do not have any intention of doing club/traveling sports that require travel until middle school when we could be traveling for school sports anyway. If my child is interested in sports that require travel, we will decide based on what our time and financial budgets allow. She will be welcome to do as many afterschool activities as she likes as long as they don't negatively impact her academics, don't conflict with each other, and are affordable. I don't personally have the capacity to do more than one activity that would require travel at a time.
Add: our afterschool activities are part of our childcare as our district doesn't have standard afterschool options. She will be able to pick from some free play options, music lessons, dance/gymnastics, organized sports, etc. as she gets older.