The NBA problems feel like a perfect storm. They waded full force into the culture wars and lost on a host of issues from defund the police, to BLM, etc. In addition their stars and faces of the league, from Lebron to Steve Kerr sold completely out to one side of the political aisle and very clearly told large portions of their fan base that they did not want their support. Shockingly telling the majority of your fan base that you don't want their attendance or viewership has consequences. When that is combined with an increasingly boring and soft product without legit universal stars it is a recipe for implosion.
Fortunately the NHL managed to dodge a lot of this at the last second. Dropping the "month" jerseys and steering away from political hot button issues managed to make them an alternative for people who just wanted entertainment. In addition, the NHL's refusal to properly promote their stars has meant that they managed to retain the team's importance above the player so team loyalty has better survived in the era of Free Agents. Also, quite frankly the NHL retains a men's culture of unselfishness, toughness and sacrifice that the NBA lost decades ago and as that culture grows in relevance (i.e. rise of MMA, elevation of football, etc.) the NHL is better positioned to ride that wave then get swamped by it.
All that sits on top of the fact that the rise in scoring and the method of scoring now means every possession is less important and less relevant even in close games. While the number of competitive games dwindles because players organize and choose to play together via UFA. And finally the fact that paying fans never know if they will actually get to see star players, because they have so many rest days, is insane. All problems that the NHL has managed to avoid due to its culture.
