I have no qualms with HWs but the facts are the facts. There is a clear skill difference, albeit I will admit not nearly as wide as it is in MMA. The same can be said largely in many other sports, I.e basketball with taller people. When you enter ranges of the population that are not as prominent you will run into other physical shortcomings.
It is also very relevant. We are talking about the most integral chapter in combat sports history. For one not to be informed on the subject puts their entire existence in that realm into question.
Allow me to go on a tangent to something I find more interesting?
You touched an area that interests me more and obsesses sherdog: big people and skills. There are two parameters I often see completely wrong (or unfairly treated) in the forums here plus a third one (*). First that bigger men have less "technique", whatever is meant by that. A technique is a learned and developed movements. Some movements are either harder or easier to execute as you get bigger: usually just gets harder. In many sports, moving around longer and heavier limbs is more difficult: we don't see tall gymnasts for example, most "acrobatics", i.e. hand eye coordination gets harder to teach to bigger kids. This is not true for other sports, of course: free-style swimming benefits from size, but long distance running does not. The list is long, all curves are quite complex in the "morphology"-"ability" space.
The other point you also touched: demographics or "gene pool". Chances are that a predisposition to execute certain movements "better" will be found in larger population samples. So, take a truly global sport: soccer. It takes its own mix up of "technique" or "fundamentals", the innate abilities, lets call it "talent" and turns out most soccer players only slightly taller and bigger than their population of origin (it's been measured, we can dig it in google scholar). One caveat is that soccer doesn't rely a lot on balls flying high (like volleyball and basketball), and although there is contact, the fouls are controlled so the sport privileges smooth movement (or at least tries to) as opposed to Rugby and our football. So, top soccer players are insanely talented, but not particularly "misshaped" relative to the population.
This is not true in sports where being bigger carries an advantage, especially the sports that are popular in america: basketball and football, (and, to an extent, baseball - but guys got big here for power....). Here's where it gets interesting: where is it that a player has the "right size" and the "perfect technique" to be a major game changer? In Basketball, there have been exceptionally skilled tall player: to perform some of their feats, carrying those frames is not easy. Michael Jordan is not a small man, and he executed motions that a lot of super talented smaller men could not pull off WHILE facing the big defenders. The acrobatics and so on, sure, smaller players will tend to execute them with greater ease: but hats off to the big guy who can use them effectively.
That said, this generalisation that "bigger men" are sloppier, not technical and so on, is usually an oversimplification, or straight out unfair. If you happen to be a giant, and need to "fight other giants", the sets of tools that are useful and at your disposal differ from those employed by smaller men.
This is why I brought the golden age of HW boxing: it was a period of highly technical, olympic-medalist boxers who performed complex movements carrying massive frames. Unfortunately, this era died... we had Tyson who was carved by D'amato (study Tyson's style, it's fascinating) and then interest in boxing changed a lot.
The * I mentioned earlier: there is a subsection of sherdoggers who are obsessed with the idea that there are "A-level" athletes in the NBA/NFL that, if they did MMA instead, would completely dominate the sport. They are partially correct: it's a great gene pool. But they are incorrect in how narrowly they define of athleticism altogether.
In any case: I don't think the topic of whether boxing will be thriving or not is important, because it's too speculative right now. Honestly, whatever sells the most and attracts people will be most popular, and MMA is in the right direction. For example, it has huge potential to grow in Asia, and that might completely reshape MMA market. But it's a parameter we've been waiting for a few years already. And boxing, as a discipline, might become a symbiotic part of MMA, with its own pure form thriving in the amateur scene and in a lower key professional scene. I'd guess more or less that, which is exactly what you predicted: but I wouldn't dare sentencing it as a definitive trend.