According to a report from the WallStreet Journal [WJS], Apple may launch an iPhone 8 with a curved display for
2017. 

For Curved Screen model, Apple has been relying on LG Display, Japan Display
and Sharp for supply of its retina displays, which use LCD technology. But
LG Display, Japan Display, and Sharp are behind Samsung when it comes to OLED
investment.

wall-street-journal-wjs-Apple-iPhone 8-Curved-Display-screen-2017
Image Source: Martin Hajek
The WSJ says that Apple has more than 10 prototypes screen including curved
display model but not released with an OLED display next year. As far as
expected we’ve been hearing reports from various sources as the 10th
anniversary iPhone 8 will be a major update to feature glass casing in order to support wireless
charging, OLED display, 3D camera, bezel less and more.
Source [9to5mac]