According to reports Apple moving to 3 year iPhone refresh cycle
'Apple will likely take three years between full-model changes of its iPhone devices, a year longer than the current cycle. In a typical two-year term, fall 2016 was supposed to see a major upgrade. But the changes on the model to be launched this autumn will be minor, such as improved camera quality'
Japanese newspaper Nikkei reports that, this move is largely due to smartphone functions having little room left for major enhancements. A slowing market is another factor.
the 2017 model will likely involve major enhancements and design changes, including adoption of an organic electroluminescent display. The new device will also be able to create more complex tactile vibrations on the display because of a tiny, but high-performance motor equipped inside..
Less frequent redesigns will significantly affect large-lot suppliers in Japan, Taiwan and other parts of Asia because of their heavy reliance on iPhone manufacturing.
The new version slated for this autumn will look almost identical to the current iPhone 6. Functions such as the camera, water resistance and battery capacity will likely be improved, and the headphone jack will be removed. Also, a high-end version of the model will give users better-quality photo capabilities via correction functions.
Apple sold some 230 million handsets in 2015, but unit sales will likely be less this year. According to Apple's production schedules provided to suppliers, the company is not expecting to sell more iPhones than last year.
On the other hand, the 2017 model will likely involve major enhancements and design changes, including adoption of an organic electroluminescent display. The new device will also be able to create more complex tactile vibrations on the display because of a tiny, but high-performance motor equipped inside.
When we talk about Apple design change and refresh cycle, according to their product development scenes, there is no need for it. Because Apple is winning by almost every measure except the one that doesn't matter at all, Market Share. There is no need for them to shorten their iPhone product cycle and if they did, it would likely do more harm than good.
Technically, Hardware development takes a long time. A fully integrated system like the iPhone requires chip design, OS implementation and application development, as well as the design and construction of the actual phone. The timeline for going from market requirements to silicon for a large SoC like the A9X is at least a year, probably more like 2 years. You can't wait one device is released to start to analyse what you're going to do next. For large hardware companies generally, when one device is released, there are 3-4 models in the development pipeline.
But this is Apple, and they know how to come up with surprisingly superb products.