As long as he wants Apple continue to make their phones thinner, they must switch to OLED displays. But that doesn't matter at all, because the technology is advanced and Apple he already uses it in his watch Apple Watch because of more beautiful colors, almost perfect black, and finally also because of consumption, since OLED gets by with a smaller battery than an LCD display. Of course, the rendering of colors already depends on the calibration of the display, so it is not true that every single OLED display produced has warmer colors than LCD. In addition, there are several suppliers and one of those who will most likely produce modern displays for iPhone 8, will be Japan Display, which today produces LCD displays for various Apple products.
A Japanese company should produce displays for iPhone 8 at the factory in Ishikawa, where it will start test production of OLED displays for the early next year Apple and gradually plans to change the equipment of the entire factory to prepare it for 2018, when it will be Apple prepare iPhone 8. Due to production capacities, Japan Display will be one of several manufacturers, while other possible manufacturers are Samsung and LG Display, which today own the two largest factories for the production of OLED displays in the world. The transition will most likely take place in 2018, but due to the readiness of LG and Samsung, it is also possible that modern displays will appear as early as 2017 in iPhone 7s.
*Source: Nikkan
