$4, this rumor is coming from a supply chain, and those companies are only aware of specific component orders, and little else. They wouldn't know if Apple is working with other suppliers to produce the same components, and they wouldn't be given any specific reasoning from a company like Apple, which "is not in the habit of sharing its strategic thinking with suppliers."
Furthermore, the assumption that last year's iPhone 5S and 5C launch schedule was a "mistake" is somewhat misguided, considering Apple had yet another $4 last year. And releasing the two iPhones on separate dates likely wouldn't affect customers' purchasing decisions if they know both phones will be available. "If someone wants the larger model, and it's launched a little later, they'll simply wait," Lovejoy says.
DigiTimes has been unreliable in the past, so it's important to take this rumor with a grain of salt. That said, we've heard $4 Apple would launch its 5.5-inch iPhone later in the year due to production issues with the larger model.
The next iPhone, presumably called iPhone 6, is reportedly thinner and rounder than its predecessors, and its screen will be made of a tougher glass solution partially made of sapphire, the second-hardest material that's currently being produced at $4. The iPhone will also reportedly run on an Apple-built 64-bit A8 processor and ship with the company's latest mobile operating system, iOS 8.