Nothing? The ruling is that app developers get to choose how they communicate to users, or how they charge in-app fees. The kind of shady developers you describe would simply continue to use Apple, as it benefits them to do so.
- Most legit services move to a web based Apple Pay (note to the unaware reader: this is NOT In-App Purchases and has never had 30% fees) due to the ease of implementing and lower fee (easier to do cross platform + web)
- Non-legit developers keep the In-App flow
Over time this would skew In-App Purchases to be scammy-only (and therefore, easier to spot). I'm sure people at Apple consider this possibility too – and therefore, now that there's actual competition, IAP flows will probably have to change to prevent this and compete for actual developer preference (and keep it a viable legit-developer choice)
So they should probably just scrap the 30% fee. At the very least scrap it if the user was linked directly to the app. And just make the also huge commission on the payments.
