UsernameWasTaken
Let's Go Hawks!
It is a TV product first a foremost.
Look at how many people watched the Olympics in Canada or the US. They didn't watch because of the name value of the Olympics, they watched because it is the peak of international competition where they know all the best names will be playing. Take NHL players out of the Olympics, and significantly less people will care.
The reason significantly fewer people care about the IIHF World Championship is because of the perception that it is a B-level tournament with leftover players.
NHL's version of the world cup may not draw ratings comparable to the Olympics the first few times around, but if they do it for long enough, pull out of the Olympics, and educate fans to the concept that the World Cup is the peak of competition (similar to how the Olympics has been since 1998) it will draw the same TV ratings as the Olympics and become a big money maker for the NHL.
I think that's simplistic. The Olympics themselves are associated with sporting excellence and national pride. The Canada/Sweden game in Lillehammer was widely watched in Canada despite the fact that there were no NHL players there.
Hockey in the Olympics will get extremely high ratings in Canada, whether or not NHL players are in it - although, less than if the NHL was there.
I do not think there will be much interest in the World Cup at all.