Again, this is what I think people get wrong when they talk about anticompetitive bundling.
Apple will continue to take a cut to make apps for the phone. The App Store and in-app purchases are how they take their cut today.
The bundling is anticompetitive against the potential market for third party payment providers and third party app marketplaces, sure. However, decoupling it is independent of reducing Apple's high fees. Apple will continue to charge a substantial fee for their part, even if due to regulatory compliance they offer less services to developers.
Someone would need to make a legal case directly against the fees Apple charges. I suspect that is a very challenging thing to do - least of which because they have never raised rates. The fees Apple collects have been the same since the first app was sold for iPhone, and the success has grown under that framework.