Did it occur to you that if a user is not the final authority who decides which apps should run on the device, he is not really owning the device, but merely leasing it, under some strict terms?
Consumers can continue to use app-store payments if they wish (and I bet the vast majority would), but developers and companies can no longer complain about Apple's monopoly over payment processing.
Also who is to say the developer would charge less? Let's say, for example, a company called ezpay charges $1 per transaction. If an IAP costs $10, they make $7 off the user who buys via Apple, and $9 off the user that buys via ezpay API in the app. They could lower the ezpay price to $8 and still only make $7, but why bother?
Only the tiniest % of HN idealists will pay 30% extra to have it go through Apple.
Google One already charges you less if you subscribe via web or android. They just haven't been allowed to advertise this fact in the iOS app.
Also, it should be telling that if you are using an App which only offers: Sketchy Payment Processor, that the app itself is sketchy, so just go use another app.
Flat per-transaction fees to cover operating costs is more acceptable. But Apple might make less money in that scheme. On the other hand, more developers might be willing to write apps for iOS if they weren't getting gouged by such high Apple Store fees, so Apple might even come out ahead if they reformed their pricing and payments policy.
I would certainly enjoy F-Droid for iOS.