That's a relatively recent phenomenon. Junior A leagues were more a part of the ladder in days past. Junior C used to lead to Junior B which used to lead to Junior A which led to major junior. It was a bit different because you'd have 14-year-olds showing up to try out and Junior B and C camps, and that's thankfully not a thing anymore. But there are going to be players looking for places to play. This doesn't change the numbers of players, and Junior A teams will still be using their numbers of graduated players as marketing pitches to both fans and prospective players, so they might talk more about how many of their players moved along to major junior and then to NHL teams.
I'd suspect Junior A will get a lot younger - and maybe they get out of the 20-year-old business entirely. At the end of the day, this looks like a reset to a more streamlined and hierarchical development system.
