Apple decided many years ago that they were going to make it rich by controlling as much of their product/software as they could. In the past, when I guess they put out unique and well crafted products it worked. Today, not so much. Their stuff is garbage. Apple has continuous problems with production and have used strong-arm tactics to control what people can find out and fix on their own.
You hit the nail on the head with "In 5-10 years, native iOS apps will be as common as Win32 C apps. Apple will go kicking and screaming, keeping iOS Safari behind the curve, blocking PWA progress where they can. " Personally, I don't think (hope?) that it will take 5-10 years. Right now they have less than 80% of the market. As more and more people figure out that their products are not what they used to be that market share will become less and less. At some point it will no longer matter.
To the argument that the "sales are there" all I can say is look at the statistics. I believe it's less than 1% of all app store products (regardless of which one) make money. And, the average user goes to five apps on their phones all the time. The chances you're going to write an app that actually makes anything is between slim and none. If the user can't install your app for free you're never even going to get it installed on their phone/tablet at all.
Further, the vast number of apps in the future will be PWAs and many of those will be business oriented. As you said, programmers don't want to have to write three different sets of code (realistically only two: JS and Apple - whatever they're pushing recently). And, most of those apps will be "installed" from the web page for that SaaS or your own enterprise.
Apple is done. Stick it with a fork and take it out of the oven. Obviously, with all the dumb money they've collected over the last 10+ years they could do well without ever shipping another product. And, without a doubt, they will continue to get people to buy their products for sometime in the future. But, they will either come to the realization that they have no choice but work with MS and Google in allowing PWAs or they will become irrelevant. It will take them some time to understand that since they no longer have forward thinking management and just surround themselves with "protect our business" types. Eventually, those turkeys will be replaced (hopefully sooner rather than later - we still need competition) or Apple will become the next Oracle. No longer a player in today's world.
And for those doubters out there, don't forget, Apple was going down when they brought Jobs back the last time. Unfortunately, they have no one to go back to this time. It can, and will, happen again.