[Apocryphon]

1) One wonders if it would be possible for Apple to disable certain types of apps regardless of how they're obtained, including alternative browser engines. I think already the OS can prevent apps from overstepping its permissions system already? Though jailbreaking can still override that.

2) That would explain greater developer demand for a third party store on iOS, but not why users would seek out these more ad-intensive app stores.

3) Yeah, this would be a pretty major reason to drive third party app stores on iOS, though it's not as if there's a ton of sideloading on Android to get around the Play Store's own 30% cut, besides the high-profile Fortnite example.

4) Yes, and it would be annoying fragmentation if other major developers/publishers did the same on iOS, requiring the installation of a ton of third party app store apps and keeping track of different app store accounts.

But how many would really go through the hassle of building their own app store just to sell their products? (Maybe it'd be easier to find a way to sell and distribute their apps through their mobile browser sites.) One would suspect the number of alternate app stores to stabilize over time.