When I watch ladies figure skating I want to see women and not little girls. And I want them to have both a childhood and a decent senior career.Those kind of problems about parents, coaches, doctors pushing the skaters won't be solved just by pushing the age eligibility to 17 or 18. Junior men mostly only move up to senior when they are 17-18, despite the age restriction. It doesn't stop them from learning billions of quads since 12. I think 15 is fine. You want to see the best people in the sport at their best shape. Not just people who survive puberty.
I'm very sure that they would train less until at least the age of 14 if the would change the age eligibility to 18. Money, coach/training availability etc. would be a factor. They would work more on the basics, on good technique, those kind of things.