> By both still demanding 27% fees
In the court case that led to this, the court required Apple to support third party payment processors, but rejected the claim that their 30% cut was outrageous.
The EU also has regulations limiting how much payment services such as Mastercard can charge. https://ec.europa.eu/commission/presscorner/detail/en/IP_13_...: “caps are set at 0.2% of the value of the transaction for debit cards and 0.3% for credit cards“
Given that, I don’t see how the same court could say a 3% margin for third party payment services is unfair.
Requiring a new app, on the other hand, is the trouble area. It means losing App Store reviews, and, probably more importantly, means users can’t seamlessly upgrade to a version that supports a third party payment service.
Also, if you retire the old app, you likely will lose subscribers. If you keep it around, you’ll likely see few users move to the new app.