The question is - if WN is late to the Hawaii party, and it is high competition lower margin flyers, then why should they do it at all?
I don't agree with the characterization or presumption that Hawaii is "high competition lower margin flyers." But nonetheless, to be clear, I'm not saying Southwest necessarily should rush to fly to Hawaii. In fact, at this point, given that many of the most obvious and logical Mainland-Hawaii markets for Southwest to enter have been carved up by competitors (particularly Alaska and Hawaiian), I tend to agree that Southwest probably should - at least for the time being - focus elsewhere.
Perhaps their best bet is just continuing expansion to the south and forget Hawaii altogether.
Very well may be. There, too, there are challenges though. Virtually every single plausible U.S. jumping off point and virtually every single plausible market in Latin America from those gateways is already served, in some cases by multiple competitors, including low-fare airlines. Southwest will use the brute force of its scale and still lower-than-network costs to muscle in, but it's not going to be easy. Again - it's the price of being the last one to enter.
To that end, it's actually a pretty intriguing "what if" to consider what the South Florida aviation market would look like today if Southwest had had the ability and motivation to start flying international out of FLL 10-12 years ago, possibly short-circuiting one of the major growth engines over that period for not one but two
of the largest low-cost competitors it faces today.