My personal preference would be for both senior-competing girls and boys to have reached their 17th birthdays by the commonly used marker of July 1st. What that would mean is, a skater could still become a junior competitor at age 13, but would have four years at junior level competitions in which to (hopefully) mature physically enough to at least 'look like' a senior competitor and get through basic puberty. I see nothing wrong with allowing skaters to remain juniors for two more additional years, if that is desirable. The cutoff between junior and senior would be the same as it is now.
There is a bit of an elephant in this room (thread) and I'm wondering if others may have thought of it also. Why is it that a 'junior skater' can be 13 to 19 years old (so long as that 19th birthday is July 1st or 2nd--I forget which--or later in the year , and still skating in the junior division? (Six years allows for too much diversity in growth and size.) Yet a senior skater can be as young as 15. That leaves a large amount of years for a skater to be a junior, senior, or both! Why is that? Both girls and boys mature at varying rates, but I'll bet we can all agree that even more 'mature-looking' 15 year olds still look like young teens, not even close to 'adults'.
There are Jr Grand Prixs and Jr Worlds, Jr Nationals and Sr Nationals. There is no Jr Olympics but there is a Youth Olympics. Thus there are already great competitions for juniors, and if juniors are capable of earning higher scores than most of the senior skaters, well what is wrong with that? Are the Jr competitions not considered prestigious enough for them to earn those scores there? Would it help to build in some Jr Challengers, maybe?
I doubt the age factor will be changed. If it were ever to happen, they might consider age 16 rather than 17--but any change would need to affect both girls and boys the same. (Yes, I still consider 16 and 17 year olds to be boys and girls rather than 'adults'.)
Not to get off the subject but as long as I'm putting my thoughts here, how about 1) letting both junior boys and girls skate a trixel and/or a quad (solo jump only) in the short program if they want to and are able to? Likewise, 2) how about letting senior girls skate not only a trixel but also a solo quad in the short? Finally, 3) can we please stop factoring 'ladies' PCS at only 80% of the 'mens''? Both sexes skate for the same amount of time now, do the same number of elements, and frankly, they are the same elements, period!