Horace Dediu makes an interesting point in this piece by Bloomberg:

“The narrative has been focused on the consumer demand, and the narrative needs to shift to the operator,” said Dediu, a former in-house analyst for Nokia Oyj. (NOK1V) “Apple has run out of the kinds of operators that will say yes to them.”

Also, I find this kind of loose wording Bloomberg uses leads to the fallacious idea that sales of iPhones are falling:

As Cupertino, California-based Apple sells fewer iPhones and more of its less-profitable products, its gross margin also has narrowed — to 37.5 percent last quarter from 47.4 percent a year earlier.

What they mean is proportionally fewer. As Benedict Evans notes:

Fascinating how many people think Apple’s iPhone sales are falling. That this is wrong is a matter of maths, not opinion

The growth in iPhone sales has started falling and if Apple has tapped out its viable markets it might start considering lower-cost iPhones to penetrate further. Evans again:

The commonality in phones that collectively outsell Apple isn’t features, screen size, ‘cloud’ or ‘openness’. It’s that they’re much cheaper