I would suggest that the issue of lower hockey output of players is not just isolated to Quebec; it's down across the board, as far as I can see, and this is talking with friends and families in other provinces, in both rural and urban ridings.
Where I live there used to be a fairly decent sized hockey association in our area. Been around since the 1960s. Even 10 years ago, enrollment and signups of players were down. The biggest reason at the time was not necessarily cost (though it certainly is a big factor now), but it was the prevalence of other sports, particularly the emergence of improving basketball and soccer teams in Canada, and the commensurate interest from kids due to that. Once parents figured it was cheaper to put their kids in other sports rather than the constant upgrading of hockey gear, the inordinate fees to put their kids into hockey plus fairly limited times of play (not to mention braving colder weather conditions), what was once something many kids did, is not relegated to families with deeper pockets.
I can't imagine with inflation and higher prices for everything being the way they are today, how that would not have an adverse impact. My oldest son played hockey throughout his childhood. My youngest son has no interest. Many younger kids are (sadly) more drawn to online video games or doing other activities with their friends. If their friends aren't playing hockey and have little to no interest, it will be hard for them to be an social outlier. That's just the trend nowadays in terms of activities. I think also that cost (of playing, of gear, of gas, etc.) has a bigger impact on parental decision making than previous.
Add to that the insane cost of exposing your kids to an NHL game in Canada - forget the Toronto market - other Canadian markets have tickets that are priced beyond what most people can afford. If you can, that's great. But a lot of people can't. And given that TV patterns have changed - less people have cable by choice and many people choose to only watch on demand on streaming mediums - what was once a family tradition Saturday night to watch the local CBC HNIC broadcast - well, that's no longer a given. With less exposure and other things to take the young person's attention, the allure of playing hockey was not what it once was.
Perhaps Quebec may have other social-political issues at play affecting hockey involvement, but I wouldn't know enough to speak on those topics.