Preview at WWDC likely in June, followed by September launch.
Latest Leak Suggests Apple Will Announce 'iPhone 8', 'iPhone 8 Plus', and 'iPhone X' on Tuesday
According to the developer, Apple will call the smartphones the iPhone 8 and iPhone 8 Plus (for the two LCD devices), and iPhone X (for the OLED model). These names will replace the iPhone 7s, iPhone 7s Plus, and iPhone 8 monikers that have been attached to each respective model over the past few months.
iPhone 8— Steve T-S (@stroughtonsmith) September 9, 2017
iPhone 8 Plus
iPhone X pic.twitter.com/OVLfhLxTdT