i think it's a bit uncertain what exactly the future of quads will be 10-15 years down the road. for the next few years as the new rule comes into play and adjustments are made we will see them as we have, but many of those who are landing them now are very very young. i'd argue we have seen more below senior than at senior for women. we still don't really know the entire picture of women and sustainable quads yet, its too new. developed bodies (or mid puberty bodies) will have a lot more difficulty learning and keeping them and the amount of ultra si could definitely decrease.
Agreed. Alysa Liu was quite honest that quads were too difficult for her after puberty and she made the wise, mature decision to stop chasing them.
Will some skaters keep them after puberty, able to land them with healthy body image, healthy eating habits and healthy attitude toward sport? I certainly hope so. That is one of the points of raising the age limit, I think.