Hopefully they would do more with the NHL Network if they expanded it to the States.
It could easily become a hockey haven and central location for TV coverage if done right. (Similar to the Fox Soccer Channel for Soccer Fans)
They could show international tournaments not normally shown on U.S. TV (World Juniors, World Championships, U18's, etc) and European club hockey (Spengler Cup, ECC, Conti Cup, national league championships, etc) Not to mention minor league, college, and junior hockey from here in North America.
Add all that with 24 hour hockey coverage with the occasional weeknight NHL game and it could be a huge hit with hockey fans.
The problem with a lot of your ideas is that broadcast rights to many of these tournaments are held by TSN in Canada and attract a larger audience than the NHL Network has. The NHL Network is a subsidiary of TSN and therefore the big ratings games and tournaments end up on the main network.
I would say its the American equivalent of the NCAA Men's basketball tournament. The play-in game for number 65 is shown on another network than CBS as it gets worse ratings than the rest of the tournament. That's why Spike TV or whatever network showed it the past year doesn't have more of the tournament. Showing the Worlds and World Juniors on the NHL Network live takes the same logic in Canada. I do believe that the NHL Network broadcast replays of the games TSN showed however. So for an American audience,the games would be on, just at say 1 AM ET instead of live.
As well a few of those tournaments, such as the Spengler Cup have their rights held by Rogers Sportsnet, as a result the NHL Network could not broadcast the tournament until the IIHF's (or whoever sells the rights) contract with Sportsnet is finished. As well the CHL's contract is held by Rogers Sportsnet.
The NHL Network does show an ECHL Game of the Week and the occassional NCAA game. However, the problem with games at that level and lower minor leagues is that there is no TV coverage of these leagues and the NHL Network rarely, if ever, sends their own crews to cover a game. Instead, they simply simulcast the games. So it would take a major investment by the NHL for the network to become what you hoped it would be.
What I wish the NHL Network would do is simulcast the few CIS hockey games that are shown regionally around Canada. The problem with this may be that The Score holds the rights to national CIS broadcasts in all sports and as a result the NHL Network may not be allowed to simulcast the regional broadcasts. However, I really doubt the CIS would put up a huge fuss as they want greater exposure to their sports across Canada.