Tars, how will it kill the sport? Have you seen the difference in attendance and vieweship between juniors and seniors? And don't give me the quad children speech. These come and go. History is not on their (or your side).
You say it will happen 100%. Nice, what are you willing to bet on that? Back up the talk.
Just as I wrote, with time it's gonna bring down the attention and viewership of senior category below the level of junior category - for couple of years casual fans will go along with it, but when more and more news of great, history-breaking skates, talents and records arrive from 13-17yo juniors, people are going to start scratching their heads, thinking "what kind of II-tier figure skating are we actually watching?". "Why am I paying 80$ for watching older ladies with triples, when I can watch the youngsters jumping quads for 10$?", "how is this woman (pointing to 80% of seniors) more artistic than Kostornaia?", etc..
Consequently, they will start turning those heads away to juniors or from the sport as a whole.
Same with judges - how long can they keep senior scores of program with 3s above nicely performed junior program with, lets say, two quads? It's unfair and impossible in a long run - 15,16,17yo juniors are going to dominate the top score rankings, commentators and journalists won't be able to close their eyes and mouths in regard to this fact as well.
"Fantastic skate of our new world champion, the best she delivered this whole season, beaten only by three junior scores this year, nevertheless..." - can you imagine how it's gonna influence the perception of the sport?
Think of all those 15,16,17yo Lipnitskayas, Zagitovas, Higuchis, Asadas, Kims, Kwans, Baiuls, etc. delivering year after year one of the finest mastepieces in the history of figure skating in junior category, being constantly compared with and often outshining the senior performances. What are they going to say to viewers and sponsors?
"Yeah, they're pretty good, but you know - we're for maturity and longevity" ???
It's ridiculous.