Ever since the launch of the iPhone 4s, Apple has consistently updated its iPhones once a year. The smaller iPhone SE was launched in 2016, so it is expected that the iPhone 7s will appear sometime in 2017. Apple is generally expected to adopt OLED displays for the iPhone, a first for its flagship product.
Apparently, only one of Apple's three anticipated new iPhones for 2017 will have an OLED screen, the iPhone 8. The iPhone 7s and iPhone 7s Plus, the realistic successors of the iPhone 7 and iPhone 7 Plus, would still use LCD screens. But there is a chance that some iPhone 7s versions will also have OLED screens.
Apple's switch to OLED for the iPhone should significantly improve the overall screen performance. Samsung's Galaxy S7 and Galaxy Note 7 have been widely praised for their OLED screens that offer superior features to the iPhone's LCD screen.
Accordingly, Apple's iPhone 8 will feature a 5.8-inch OLED screen with a wraparound screen different from others seen on a phone so far. The iPhone 7s will retain the likely 4.7-inch screen, and the iPhone 7s Plus will have a 5.5-inch display.
Apple may yet choose to use OLED displays in the iPhone 7s models. Two factors may influence this decision: Samsung's capacity to deliver the enough OLED screens that match Apple's requirements and depletion of Apple's existing LCD inventory. Also, it seems that other smartphone makers have also noticed of the iPhone 8 OLED rumors and are scrambling to secure OLED supply for their own handsets.
It seems that Samsung will be the only OLED display manufacturer for the iPhone. But the South Korean giant cannot possibly meet Apple's demand. That is why maybe only the iPhone 8 will not get the new OLED screens. The three anticipated new iPhone for 2017 will have to possibly settle for LCD screens.