Not at all. Minor league could easily supplant the NHL, they’re position isn’t that secure. The WHL gave them a serious run for their money for a long time, and as it faded the WHA challenged it. Right now the KHL is stealing players from it, it probably won’t challenge for a North American audience, but taking players hurts the product. And remember they LEASE the Stanley Cup, if they mismanage the business enough the Cup could go to a different league, there was talk of that during the lost season. Really that season could have killed the league, they lost ESPN, AHL gained a lot of popularity. If the Outdoor Life Network hadn’t decided on a major change in name and focus, which started with giving the NHL a contract, I don’t know where they would have been. The only other TV taker they had was a no money down revenue sharing deal with NBC that was only 40 games, 20 regular season and 20 post. The NHL was shockingly close to the “where are they now” section of People Magazine only 10 years ago. They’ve got a nice sexy contract with NBC/Universal now, but they had some nice contracts in the late 80s and early 90s and unwound all of it in about 10 years, there’s nothing saying they can’t screw it up again.
Like I said, I find the entertainment business quite fascination. A lot of sports leagues aren’t nearly as stable as they look to the casual viewer.
Interestingly, soccer tends to avoid the conflict (somewhat) through the concepts of promotion and relegation (incidentally, one would imagine that those are American concepts, and not un-American at all).