As reliance on mobile devices and their capabilities increase, this could become less of an issue.
It is still a luxury for most people - "oh cool look at this app," but it still comes down to those that can afford an iPhone. I can imagine there are many family squabbles involving parents that bought their kid an iPhone that racked up an App Store bill the parents didn't originally intend.
iPhone is not a business phone overall - and therefore doesn't have "critical apps".
If you polled a random user of, what are the chances you would find an app that they will get very pissed off at it's disappearance?
What are the chances they will actually skip platforms?
On Windows or OSX, I think the answer is high. On iphone, maybe not.