In an update on Apple’s Developer website, Apple is now requiring that new apps submitted to the company must include support for the iPhone X’s display. “Update your version of Xcode to the latest release of Xcode 9 available on the Mac App Store, which includes the iOS 11 SDK, and build your apps. Starting April 2018, all new iOS apps submitted to the App Store must be built with the iOS 11 SDK. All new apps for iPhone, including universal apps, must support the Super Retina display of iPhone X.”
This is expected to come into effect in April 2018, although the language is rather interesting because it does not specifically mention app updates. This means that this seems to only be applicable to brand new apps that are being submitted to Apple for the first time ever, which while is great for new apps, isn’t so great for users of existing apps where depending on the developer, might take them a while to push out an update that supports the iPhone X’s notch and display.