1. Entering college one, two, four, or eight years early does not have to mean leaving home earlier. Many families live within commuting distance of a decent regional 4-year (we were blessed to live within range, and were able to commute throughout undergrad; some of us were of an age that commuting during graduate school also was preferred). Many others can access reasonable online college coursework. (If attending an elite institution has particular value for an individual, there's always graduate/professional school or postdoc/residency.)
2. Particularly for females (but for males, also), buying years with grade skips can make the difference between being a young, active parent, and being an older, less agile, parent, or even being a parent at all. Especially since this population is disproportionately more likely to engage in significant further education beyond a bachelor's degree. Even without post-grad education, one can have the option of becoming more established in a career before beginning child-rearing, and still be relatively young, which can make a difference in terms of work-life balance.
* But I still maintain that a decision now one way or the other is not nearly as limiting to future options as it may feel in the moment. Do what you think is best for your child as s/he is, at this moment in time, and don't be afraid to change if it doesn't work out. It's not a failure, nor are they likely to be seriously injured by a short period of poor fit.
"Each day has enough trouble of its own."
