Canada is relying on population growth via big bursts of immigration from places where hockey doesn't exist. That's bound to have an effect on the national culture as immigrants basically need to be 'brainwashed' to think of Canada's favorites as their favorites..which can happen with the 2nd and 3rd generation but only if there's a cultural push for it.
But in a larger context, hockey is not only an expensive sport, it's also a bit of an acquired taste. It's a sport that heavily rewards size and athleticism, so a large % of kids are on the out from the get-go. It's a sport that requires a tolerance of violence and injury which again rules out a large % of kids. So you need parents that have money, have tall, athletic children and don't mind their kids getting a few teeth knocked out. I mean that just doesn't strike me as more than a niche population.