Their attitude of non-compliance with pro-consumer regulations starts to be seen as selfish.
Right now Apple has a positive brand image.
These actions have the ability to tarnish their reputation .. especially if long time developers break out of their enchantment with the ecosystem.
The legislation was initially just a list of things that Standard Oil actually did.
America will be just fine. The biggest factor perpetuating the free market and the decline of monopolies is tech progress and the MBA-ification of big companies.
Could you elaborate on this? It's not seen in practice - both tech progress and MBAs are contributors to the condensing of every industry (airlines, banks, supermarkets, office supply stores, appliance manufacurers, food manufacturers, etc.) into fewer and fewer megacorps with monopoly or oligopoly effects.
Take cable companies; they'll probably always be awful, but that also matters less and less. Or Microsoft; we all hate their awful attitude, but that old desktop paradigm just doesn't rule the world of computing anymore. Same with Google and eventually Apple.
For the other industries you mention there's been less innovation and competition. But if they ever build up a true monopoly in one of those, it will lead to higher margins for the monopoly (otherwise it isn't one!). And the higher margins attract competition.
All the industries you mentioned, especially retail and airlines, are very bare-bones industries that barely make any money. Big operators like Southwest Airlines and Walmart make 1-5% profit in good times. (Banks make more, but there are tons of regulations that prevent competition there, but the upside of those regulations might be a good thing overall).
Its really hard to break network effects, especially at Apples scale.
If it was just gonna end with a minor gatekeeping fee, I can see myself (and other) just biting the bullet but history suggests that this is just the beginning of a massive descent.
Descent of the free market - no, this is how it's supposed to work.
Monopolies can be good for a short while for the economy, although they always go sour after a while.
Standard Oil provided clean(er) and safe(r) lighting and fuel for millions around the world, developing ultra efficient refining and distribution techniques. They even saved the whales by accident.
M$ was much-reviled in the 90's, but their PC monopoly helped establish a standard for computing, which almost certainly contributed positively to the rapid development of hardware and the internet in that time.
The same is true for the iPhone ecosystem and the large-country-sized app economy it spawned.
But if Apple doesn't keep innovating (truly new products, not just newer phones and iOS'es), no amount of monopolistic action will keep them afloat and in fact would probably hasten their decline. These big corpo's become the victims of the economic and technical progress they create.
Not using a product as the code initially dictates is not actually a criminal violation, in any sane world. The law is making a fool of itself for backing software-as-law as it does.