> Why would iOS users' data be more lucrative? Spending money on the App Store is orthogonal to having more desirable data to sell.

This just isn't true. The data of people who have more money to spend is more attractive than that of those who do not. Also having more money to spend means that data can be used for targeted advertising or just knowing what people with money are interested in and where to focus efforts.

> Easy to conceive, difficult to execute. This scenario might have been feasible a decade ago, when Facebook was younger, their brand was fresher, and customers less jaded.

I mean, if you are still on FB and use it regularly there really isn't much hope for you at this point. I don't get the impression that there is a large number of people on FB saying "If they step over the line 1 more time I'm leaving", at this point it's people who just don't care. To some degree the same is true for IG even though it's users like to think it's different. It doesn't even have to be new features, it could just be something like groups (which I think failed) or messenger that they take away features or apps and only release them on their own store. They can even make a big hullabaloo about "This lets us get fixes and features out to you faster and lets you easily opt into our beta channel".

> And why wouldn't EU/US courts apply antitrust laws against them? Why is antitrust law assumed to be only used against Apple now, when legislators/regulators are miffed at all the large tech companies?

Why haven't they indeed? Their bad behavior is clearly visible, I'm completely unclear as to what the EU doesn't seem to care. They seem to be laser focused on mobile to the determinant of desktop and consoles.

> I find the whole hypothetical of third party iOS app stores fascinating, because any examination into the landscape of app ecosystems show that they are bloody difficult to build. Ask Microsoft with the Windows Phone Store, or RIM with the BlackBerry Marketplace. Or just Amazon and Samsung with their third party Android app stores, which seem to exist mostly to service users on their own OEM Fire or Galaxy devices.

MS had devices/OS that no one wanted, RIM was late to the game and had their lunch eaten by that point. As for Amazon/Samsung they capture a lot of a value by making themselves the default but more importantly, all of these examples are platform providers, not app developers (at their root). Meaning, they make their money by taking a cut, not by selling apps themselves or even through ads in apps (maybe ads in their store). The calculus changes for someone like FB, EA, EPIC, etc, especially for less savory app creators who don't care about privacy. I'm not saying that FB will create a store and become the number 1 app store, but that they will release their apps via their own store (with it's own rules, or lack thereof) and users will be forced/tricked/incentivized into using it.

> The idea that Facebook or Google can just make third party app stores and everyone will flock to them is just a questionable, reductionist scenario that flies in the face of creeping consumer burnout in the present day, and all of the failed app stores of the past.

Flock to? Probably not and that's not even what I'm afraid of/worried about. It's being forced into using third-party stores. Either by the company removing their app from the Apple App Store or by gating features to the app only if it was installed via their store.