Apps based around "physical goods" (read: food ordering) have been able to do this for ages, and if the trend I see there expands into "normal" apps, about 50%

Apps based around "physical goods" (read: food ordering) have been able to do this for ages, and if the trend I see there expands into "normal" apps, about 50% will support Apple Pay, 25% will support PayPal without AP, 10% will support card scanning, and the rest will make you manually enter your card number, billing address, name, email, firstborn child, etc. So no, I don't think the flow will remain nearly as seamless as it is today, and that's disappointing to me. I don't pay for much IAP-wise (though I do order plenty of DoorDash), but I guess this will give me even less motivation to buy crap I don't need.