I'm absolutely against raising the age limit.
First because of biology. Not everyone is built the same. There are skaters who grow faster than others and are more shapped than other skaters of their age or even older. If we compare Daria Panenkova, Anastasiia Gubanova at 15yo with Trusova, Shcherbakova, Kostornaia at the same age, it looks like the two first are at least 2 years older than the other three. When i watched JGPs this season, i had an hard time believing that some skaters were the same age than Petrosian (14yo) who is very small.
Then i don't see why everyone should get the same treatment. Some skaters don't have that "unfair physical advantage" over 17yo skaters since they are as curved, if not more.
And about stamina capacity, i don't see much difference between 15yo and 17/18yo. 17/18yo is still fairly young.
2nd, because i think it won't resolve anything about the technical side. When they fixed an age limit, did it stop coaches to teach 3-3s from 11yo? Now skaters are learning quads from 10yo. If we add 2 more years to age limit, does it mean that they will start to learn at 12yo? I don't see much difference anyway, they are still young bones.
3rd, because among reasons that people who want the age limit to be raised give, there is the "i'm tired to see children with women. Skating at senior level should be for skaters who looks like women". It's incredibly unfair. Not because of the supposed body-shame, i don't see body shame, there are skaters who really look like children younger than 15yo. But because this is a sport and aesthetics should be really secondary. If an athlete worked hard to get a certain level, he should be allowed to show what he/she learnt, no matter if she doesn't have boobs or he have too much baby cheeks. No one choose their body type or their growing speed. Tursynbaeva, Uno and Samsonov didn't choose to look 5 years younger when they were 15yo. If skaters have the same skills than seniors, they should be allowed to compete, no matter what they look like.
And finally, those older skaters were 15yo once and were free to get the same results. If they didn't, it isn't the fault of the current 15yo skaters. Tuktamysheva was allowed to compete (and win medals) at grand prix series at 14yo. I don't think she would have took it well if ISU had suddenly told her "you're too young and have an unfair advantage over older skaters, you can't compete.".
So, it should be 15yo. And not by the 1st july. If you are 15yo during a competition you should enter if you can, no matter when you turned 15yo.
If it's raised, i hope at least that all skaters who already debuted on junior level will be exempted.