Like others have said, hockey is declining in Canada. In large part, it's Hockey Canada's failure to grow the game. Plenty of kids from immigrant families love to watch hockey, collect cards, play street hockey or even join ball hockey leagues. Thing is, most of their parents can't afford to put there kids in ice hockey and so you have the typical white privileged kids taking up all of the ice time at the rinks, getting the best gear, attending camps and such. Hockey Canada pushes these things under the rug like they always have and fail to make the game more affordable or market it appropriately. It wasn't so much of a problem in the past as the inflation in Canada wasn't as bad, other countries still lagged behind Canada in terms of player development and the pool of players to choose from was larger. Now, European countries have surpassed Canada in some areas of development such as goaltending. Additionally, USA hockey has done a great job of implementing cost-effective programs across the country to increase player enrolment.
That being said, I don't think the situation is as grave as you're making it out to be. Canada has always produced more centres than wingers. If you look at the 2016 WCOH team, you'll see that a majority of the players were centres: Crosby, Toews, Getzlaf, Bergeron, Tavares, Stamkos, Thornton, Giroux, Duchene and Couture. The only true wingers on the team were Marchand and Perry. Canadian hockey has always emphasised strong two-way play and forechecking and thus, more centres are produced than wingers. It's not like Canada doesn't have elite wingers right now either. Huberdeau, Marner, Stone, Marchand and Kyrou are all natural wingers.
I see a future where USA Hockey and Hockey Canada are on par with one another. They'll be periods where one is stronger than the other, but I think it's safe to say that Canada's run of being the sole hockey superpower is coming to an end.