I admit I'm ignorant in curling: what countries are the "powerhouses"?
In Mens Canada and Sweden are the powerhouses. They have won 8 (Canada-6 Sweden-2) of the last 10 World Championships with Canada has won 3 of the last 4 Gold at Olympics.
Norway, Scotland and Switzerland have had their moments as well but they are not as consistent as Canada and Sweden.
The Womens game seems to have more variance. The Canadian women are at the top but nowhere near as dominant as the men.
As for Shuster, I am obviously a non-believer and as someone said we'll see what it means but I think this is much more of a Mike Harris great run type of deal than a team starting to emerge as a consistent threat. They have been around ling enough and easily beat so many times I doubt they miraculously found something to change that.