Would be stupid to say that though when the iPhone is a massive halo product. A lot of their other revenue would dry up if the iPhone stopped selling. Revenues from Services, which rely heavily on being used on i-Devices would likely drop. Less iCloud usage. Possibly less iTunes usage. Other would also dry up, as at least two of the groups in "Other" would likely lose sales. How much does the Apple TV, or the Accessories rely upon the iPhone sales? What about the Apple Watch? which wouldn't sell at all without the iPhone. And they can't really fall back to the iPod. that horse is dead.
What about brand power that the iPhone brings? Along with the iPhone, Mac sales also started to increase dramatically around the same time as the iPhone launch. I don't think it's any coincidence that iPhone sales impact Mac sales with brand recognition. "I have an Apple phone and I love it, hey, I hear they make computers too!"
THIS is why Investors a freaking out over seemingly small dip in revenues. Without the iPhone selling, all the other product categories Apple is in is believed to drop alongside. WIthout the iPhone, they likely wouldn't have 17-20bn from other revenues.