Eighty percent -- roughly the amount of estimated revenue derived from the top handful -- as in six! -- teams
Ten percent -- roughly the amount of games lost due to labor and management issues in the past decade.
Which means, well, two things.
First, in regards to the first point, there is no earthly reason why there should be thirty teams. This isn't the usual talent issue that people bring up whenever a league goes to expansion; I don't pretend to be even remotely qualified to judge such things. But I do know that when a league has an incredible revenue disparity, and will likely have the exact same disparity ten years from now regardless of who wins and loses... that isn't a league. That's a fiefdom where the serfs don't really have a good reason to exist.
Second, the games lost issue basically means that the league is no longer able to be a secure purchase on a corporate level. The thing about labor issues and the power that the NHL has over its core demographic is that the fans are always going to come back; the game is in their blood, especially for Canadian single markets and the American members of the Original Six (and some of the more established older markets). But the luxury boxes are another matter entirely.
Entertaining clients and providing a perk to fat cats only works if, well, there are games to go to. If you buy a luxury box for NBA, MLB or NFL games, you've had minor labor hiccups and the occasional embarrassment like a steroid scare or scab refs... but nothing like wasted years on multiple occasions that makes you wonder if there's even going to be a league. And corporate guys aren't really all that fussy about what game they are seeing on their night out. They might prefer hockey to hoops or something else (boxing, a concert, etc.), but the real win is the night out at an event.
If the NHL loses corporate money -- and given the 10 percent and growing number, it's more of a certainty than a probability -- that means the 80% number is going to get worse, not better. And if that happens, it's really hard to not see how those weaker franchises don't go away even faster...
And, well, there are other hockey leagues, in other countries, that have been taking back their talent with open arms and speed.
So this isn't the usual money grab of billionaires against millionaires, even if that's how the owners or players feel about it. Because they've been down this road too many times already, and burned too many bridges behind them.
There will always be hockey, and there will likely always be an NHL; it's the best league in the world in the market with the most money to spend on it. But there doesn't have to be 30 teams, 82 games, and 6+ months of games before it gets really good... especially when you could make nearly the same amount of money while losing a third of the teams and games. And it's not as if the lost markets couldn't live with minor leagues, juniors and college games...