I wonder if Apple is allowed to put warnings on apps that contain directions to non-app store payments. Something like "This app may direct you to a payment method not reviewed by or governed by the App Store's strict security guidelines. Use at your own discretion. Apple is not responsible for any issues related to this non-Apple payment method."
Apple is far more likely to just require a cut from in-app sales transacted through any other mechanism, something Apple is still legally entitled to, and can be clarified in the developer terms which must be signed in order for others to sell products which integrate Apple intellectual property.
