It's being reported by DigiTimes that Samsung Display will be the "exclusive suppleier of AMOLED panels" for use in the 2017 iPhone. As you might recall, we'd already heard that Apple is planning a complete overhaul of the iPhone lineup for next year and switching up the display tech is one big part of that.
As you are likely already aware, AMOLED screen tech allows for deeper blacks and more vibrant colors. An AMOLED iPhone would certainly make for a more pleasing video-watching and game-playing experience. Your Instagram posts will look better too.
The reason why Apple is reportedly tapping Samsung for AMOLED panels is that the latter is the only company reportedly capable of supplying the 20 million units needed each month. Interestingly, AMOLED is apparently only going to be found on the largest 5.8-inch iPhone 8, whereas the 4.7-inch and 5.5-inch models will stick with TFT-LCD.