If Apple were to be required to allow third party App Stores or side loading apps, could it legally deny interoperability with Apple services as a “security measure,” like a sandbox? For example, you can download a game, but it won’t hook into their gaming social network. No ability to share in iMessage, or sync data to iCloud. Basically cripple the apps so that for the end user it isn’t worth saving the money on the apps that don’t have the 30% markup.
In my experience, if there's an option to ask same price everywhere, sellers will do that. So on app store it will cost (for example) 4.99$, and on third party app store without 30% cut, the developers will still set the price of 4.99$.
The only kind of place I've seen prices less than MSRP is discount stores like cdkeys. For example, try to find microsoft windows that costs less than MSRP -- on all stores, first party and third party, the price will be the same.
So, lack of 30% markup is very unlikely to reduce the final asking price by 30%.
If this is the case, I see no particular reason to go through the hassle of a 3rd party App Store or side loading on iPhone. But, my time vs $ saved equation is different from lots of people, so I suppose it would appeal to some users at even a 10% discount or less.
I'm sure both the developers and the consumers will still choose to use the sideloaded app depending on the app. Look at how Fortnite on Android skipped the entire Google Play Store because they can provide the entire infrastructure themselves anyways.
Or apps that get denied from the Apple App Store. Emulators come to mind, but also the recent Steam Link app is still not allowed on the App Store.
